Semiconductor light emitting device

ABSTRACT

There is provided a semiconductor light emitting device including a conductive substrate, a first electrode layer, an insulating layer, a second electrode layer, a second semiconductor layer, an active layer, and a first semiconductor layer that are sequentially stacked. The contact area between the first electrode layer and the first semiconductor layer is 3% to 13% of the total area of the semiconductor light emitting device, and thus high luminous efficiency is achieved.

RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No. 13/125,256filed on Jul. 11, 2011 which is the U.S. National Phase under 35 U.S.C.§371 of International Application No. PCT/KR2009/006144, filed on Oct.22, 2009, which in turn claims the benefit of Korean Application No.10-2008-0103671, filed on Oct. 22, 2008 and Korean Application No.10-2009-0100912, filed on Oct. 22, 2009, the disclosures of whichApplications are incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a semiconductor light emitting device,and more particularly, to a semiconductor light emitting device capableof performing an operation at a high current and improving luminousefficiency by changing an electrode arrangement structure.

BACKGROUND ART

Semiconductor light emitting devices include materials that emit light.For example, light emitting diodes (LEDs) are devices that use diodes,to which semiconductors are bonded, convert energy generated by therecombination of electrons and holes into light, and emit the light. Thesemiconductor light emitting devices are widely used in applicationssuch as lighting, display devices and light sources, and the developmentthereof has been expedited.

In general, semiconductor junction light emitting devices have ajunction structure of p-type and n-type semiconductors. In thesemiconductor junction structure, light may be emitted by therecombination of electrons and holes at junction regions of both typesof semiconductors, and further an active layer may be formed betweenboth types of semiconductors in order to activate light emission. Thesemiconductor junction light emitting devices have a vertical structureand a horizontal structure according to the positions of electrodes forsemiconductor layers. The horizontal structure includes an epi-upstructure and a flip-chip structure.

FIG. 1 is a view illustrating a horizontal semiconductor light emittingdevice according to the related art and FIG. 2 is a cross-sectional viewillustrating a vertical semiconductor light emitting device according tothe related art. For convenience of explanation, in FIGS. 1 and 2, adescription will be made on the assumption that an n-type semiconductorlayer is in contact with a substrate and a p-type semiconductor layer isformed on an active layer.

First, a horizontal semiconductor light emitting device will bedescribed with reference to FIG. 1.

A horizontal semiconductor light emitting device 1 includes anon-conductive substrate 13, an n-type semiconductor layer 12, an activelayer 11, and a p-type semiconductor layer 10. An n-type electrode 15and a p-type electrode 14 are formed on the n-type semiconductor layer12 and the p-type semiconductor layer 10, respectively, and areelectrically connected to an external current source (not shown) inorder to apply voltage to the semiconductor light emitting device 1.

When voltage is applied to the semiconductor light emitting device 1through the electrodes 14 and 15, electrons move from the n-typesemiconductor layer 12 and holes move from the p-type semiconductorlayer 10, which results in the recombination of the electrons and theholes to emit light. The semiconductor light emitting device 1 includesthe active layer 11 and the light is emitted from the active layer 11.In the active layer 11, the light emission of the semiconductor lightemitting device 1 is activated and light is emitted. In order to make anelectrical connection, the n-type electrode 15 and the p-type electrode14 are positioned on the n-type semiconductor layer 12 and the p-typesemiconductor layer 10, respectively, with the lowest contact resistancevalues.

The positions of the electrodes may be varied according to substratetypes. For instance, in the case that the substrate 13 is a sapphiresubstrate that is a non-conductive substrate as shown in FIG. 1, theelectrode of the n-type semiconductor layer 12 cannot be formed on thenon-conductive substrate 13, but should be formed on the n-typesemiconductor layer 12.

Therefore, when the n-type electrode 15 is formed on the n-typesemiconductor layer 12, parts of the p-type semiconductor layer 10 andthe active layer 11 that are formed at an upper side are consumed toform an ohmic contact portion. Since the electrodes are formed in thisway, a light emitting area of the semiconductor light emitting device 1is reduced, and thus luminous efficiency also decreases.

In order to solve a variety of problems including the above-describedproblems, a semiconductor light emitting device that uses a conductivesubstrate, rather than the non-conductive substrate, has appeared.

A semiconductor light emitting device 2, as shown in FIG. 2, is avertical semiconductor light emitting device. Since a conductivesubstrate 23 is used, an n-type electrode 25 may be formed on thesubstrate. Although, as shown in FIG. 2, the n-type electrode is formedon the conductive substrate 23, a vertical light emitting device mayalso be manufactured by growing semiconductor layers by using anon-conductive substrate, removing the substrate, and then directlyforming an n-type electrode on an n-type semiconductor layer.

When the conductive substrate 23 is used, since voltage can be appliedto an n-type semiconductor layer 22 through the conductive substrate 23,an electrode may be formed directly on the substrate.

Therefore, as shown in FIG. 2, the n-type electrode 25 is formed on theconductive substrate 23 and a p-type electrode 24 is formed on a p-typesemiconductor layer 20, thereby manufacturing a semiconductor lightemitting device having a vertical structure.

However, in this case, particularly in the case that a high-power lightemitting device having a large area is manufactured, an area ratio ofthe electrode to the substrate needs to be high for current spreading.As a result, light extraction is limited and light loss is caused due tooptical absorption, and further luminous efficiency is reduced.

The horizontal and vertical semiconductor light emitting devices, whichare described with reference to FIGS. 1 and 2, have a reduced lightemitting area to reduce luminous efficiency, limit light extraction, andcause light loss due to the optical absorption.

For this reason, a semiconductor light emitting device having a newstructure needs to be urgently developed in order to solve the problemsof the conventional semiconductor light emitting devices.

DISCLOSURE Technical Problem

An aspect of the present invention provides a semiconductor lightemitting device having a new structure.

An aspect of the present invention also provides a semiconductor lightemitting device with high luminous efficiency.

An aspect of the present invention also provides a high-currentsemiconductor light emitting device.

Technical Solution

According to an aspect of the present invention, there is provided asemiconductor light emitting device including a light emitting structurehaving a conductive substrate, a first electrode layer, an insulatinglayer, a second electrode layer, a second semiconductor layer, an activelayer, and a first semiconductor layer sequentially stacked. Here, thesecond electrode layer includes at least one exposed region formed byexposing a portion of an interface in contact with the secondsemiconductor layer. The first electrode layer penetrates the secondelectrode layer, the second semiconductor layer, and the active layerand is electrically connected to the first semiconductor layer by beingextended to predetermined regions of the first semiconductor layerthrough a plurality of contact holes penetrating the predeterminedregions of the first semiconductor layer. The insulating layer insulatesthe first electrode layer from the second electrode layer, the secondsemiconductor layer and the active layer by being provided between thefirst electrode layer and the second electrode layer and on sidesurfaces of the contact holes. A contact area between the firstelectrode layer and the first semiconductor layer is 0.615% to 15.68% ofa total area of the light emitting structure.

The contact holes may be uniformly arranged.

The number of the contact holes may be 1 to 48,000.

The contact area between the first electrode layer and the firstsemiconductor layer may be 6,150 μm² to 156,800 μm² per 1,000,000 μm²area of the semiconductor light emitting device.

A distance between central points of adjacent contact holes among thecontact holes may be 5 μm to 500 μm.

The semiconductor light emitting device may further include an electrodepad portion formed on the exposed region of the second electrode layer.

The exposed region of the second electrode layer may be formed at acorner of the semiconductor light emitting device.

The second electrode layer may reflect light generated from the activelayer.

The second electrode layer may include one selected from the groupconsisting of Ag, Al, Pt, Ni, Pt, Pd, Au, Ir and a transparentconductive oxide.

The conductive substrate may include one selected from the groupconsisting of Au, Ni, Al, Cu, W, Si, Se, and GaAs.

The contact area between the first electrode layer and the firstsemiconductor layer may be 3% to 13% of the total area of the lightemitting structure.

According to another aspect of the present invention, there is provideda semiconductor light emitting device including a conductive substrate;a light emitting structure having a second semiconductor layer, anactive layer, and a first semiconductor layer sequentially stacked; afirst electrode layer including contact holes in contact with an insideof the first semiconductor layer by penetrating the second semiconductorlayer and the active layer and an electrical connection portion extendedfrom the contact holes and exposed outwardly of the light emittingstructure; and an insulating layer electrically separating the firstelectrode layer from the conductive substrate, the second semiconductorlayer and the active layer. Here, a contact area between the contactholes and the first semiconductor layer is 0.615% to 15.68% of a totalarea of the light emitting structure.

DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a horizontal semiconductor light emittingdevice according to the related art;

FIG. 2 is a cross-sectional view illustrating a vertical semiconductorlight emitting device according to the related art;

FIG. 3 is a plan view illustrating a semiconductor light emitting deviceaccording to an exemplary embodiment of the present invention;

FIG. 4 is a cross-sectional view illustrating a semiconductor lightemitting device according to an exemplary embodiment of the presentinvention;

FIG. 5 is a graph illustrating n-type ohmic contact resistance andp-type ohmic contact resistance of a semiconductor light emitting devicehaving an area of 1,000×1,000 μm²;

FIG. 6 is a graph illustrating the total resistance of a first contactresistance and a second contact resistance according to the contact areabetween a first semiconductor layer and a first electrode layer;

FIG. 7 is a graph illustrating luminous efficiency according to thecontact area between the first semiconductor layer and the firstelectrode layer;

FIG. 8 is a view illustrating a modification of the semiconductor lightemitting device of FIG. 4;

FIG. 9 is a cross-sectional view illustrating a semiconductor lightemitting device according to another exemplary embodiment of the presentinvention;

FIGS. 10 and 11 illustrate the result of a simulation conducted bychanging n-type specific contact resistance;

FIGS. 12 through 16 are views illustrating a semiconductor lightemitting device according to another exemplary embodiment of the presentinvention;

FIGS. 17 through 20 are views illustrating a semiconductor lightemitting device according to another exemplary embodiment of the presentinvention;

FIGS. 21 through 25 are views illustrating a semiconductor lightemitting device according to another exemplary embodiment of the presentinvention;

FIGS. 26 through 36 are views illustrating a semiconductor lightemitting device according to another exemplary embodiment of the presentinvention;

FIGS. 37 through 57 are views illustrating semiconductor light emittingdevice according to another exemplary embodiment of the presentinvention;

FIGS. 58 through 77 are views illustrating semiconductor light emittingdevice according to another exemplary embodiment of the presentinvention;

FIGS. 78 through 91 are views illustrating semiconductor light emittingdevice according to another exemplary embodiment of the presentinvention;

FIGS. 92 through 102 are views illustrating a semiconductor lightemitting device according to another exemplary embodiment of the presentinvention;

FIGS. 103 through 105 are schematic views illustrating variousembodiments of a white light emitting device package according to anexemplary embodiment of the present invention;

FIG. 106 illustrates the light emission spectrum of a white lightemitting device package according to an exemplary embodiment of thepresent invention;

FIGS. 107A through 107D illustrate the light emission characteristics ofgreen phosphors applicable to the present invention;

FIG. 108A and FIG. 108B illustrate light emission spectrums showing thelight emission characteristics of green phosphors applicable to thepreset invention;

FIGS. 109A and 109B illustrate light emission spectrums showing thelight emission characteristics of yellow phosphors applicable to thepresent invention;

FIGS. 110 and 111 are cross-sectional views illustrating white variousembodiments of a white light source module according to anotherexemplary embodiment of the present invention;

FIGS. 112 and 113 are schematic views illustrating various embodimentsof a light emitting device package according to another exemplaryembodiment of the present invention;

FIGS. 114A through 114C are schematic views illustrating the process offorming an external lead frame in the light emitting device packagedepicted in FIG. 112;

FIGS. 115 through 117 are graphs showing the X-ray diffraction analysisresult, light emission spectrum and excitation spectrum of β-sialonphosphors manufactured according to inventive example 1;

FIGS. 118 and 119 are schematic perspective views illustrating a surfacelight source device having a flat light guide plate, and the light guideplate according to an exemplary embodiment of the present invention; and

FIGS. 120 through 125 are views illustrating a backlight unit having aflat light guide plate according to another exemplary embodiment of thepresent invention.

MODE FOR INVENTION

Exemplary embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

The invention may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the inventionto those skilled in the art. In the drawings, the shapes and dimensionsmay be exaggerated for clarity, and the same reference numerals will beused throughout to designate the same or like elements.

First, a semiconductor light emitting device will be described in detailthrough a variety of exemplary embodiments, and a light emitting devicepackage and a backlight device using the same will also be described.

<Semiconductor Light Emitting Device>

FIGS. 3 and 4 are a plan view and a cross-sectional view illustrating asemiconductor light emitting device according to an exemplary embodimentof the present invention. Here, FIG. 4 is a cross-sectional view takenalong a line I-I′ shown in FIG. 3.

Referring to FIGS. 3 and 4, a semiconductor light emitting device 100according to an exemplary embodiment of the invention includes aconductive substrate 110, a first electrode layer 120, an insulatinglayer 130, a second electrode layer 140, a second semiconductor layer150, an active layer 160, and a first semiconductor layer 170 which aresequentially stacked.

The conductive substrate 110 may be formed of an electrically conductivematerial. The conductive substrate 110 may be formed of a materialincluding any one of Au, Ni, Al, Cu, W, Si, Se, and GaAs, for example,an alloy of Si and Al.

The first electrode layer 120 is stacked on the conductive substrate110. Since the first electrode layer 120 is electrically connected tothe conductive substrate 110 and the active layer 160, the firstelectrode layer 120 may be formed of a material capable of minimizingcontact resistance with the conductive substrate 110 and the activelayer 160.

The first electrode layer 120 is stacked on the conductive substrate 110and further, some portions thereof, as shown in FIG. 4, penetrate theinsulating layer 130, the second electrode layer 140, the secondsemiconductor layer 150 and the active layer 160 and are in contact withthe first semiconductor layer 170 by being extended through contactholes 180 which penetrate predetermined regions of the firstsemiconductor layer 170, whereby the conductive substrate 110 and thefirst semiconductor layer 170 are electrically connected.

That is, the first electrode layer 120 electrically connects theconductive substrate 110 to the first semiconductor layer 170 throughthe contact holes 180. The conductive substrate 110 and the firstsemiconductor layer 170 are electrically connected through areas whichare the size of the contact holes 180, more exactly, contact regions 190that are areas in which the first electrode layer 120 and the firstsemiconductor layer 170 are in contact with each other through thecontact holes 180.

Meanwhile, the insulating layer 130 is formed on the first electrodelayer 120 in order to electrically insulate the first electrode layer120 from other layers except for the conductive substrate 110 and thefirst semiconductor layer 170. In other words, the insulating layer 130may be formed not only between the first and second electrode layers 120and 140, but also between the first electrode layer 120 and the sidesurfaces of the second electrode layer 140, the second semiconductorlayer 150 and the active layer 160 which are exposed by the contactholes 180. Furthermore, the insulating layer 130 may be formed on sidesurfaces of the predetermined regions of the first semiconductor layer170 which the contact holes 180 penetrate to achieve insulation.

The second electrode layer 140 is formed on the insulating layer 130. Asdescribed above, the second electrode layer 140 is not formed on thepredetermined regions which the contact holes 180 penetrate.

Here, the second electrode layer 140, as shown in FIG. 4, includes atleast one region where a portion of an interface in contact with thesecond semiconductor layer 150 is exposed, i.e., an exposed region 145.An electrode pad portion 147 may be formed on the exposed region 145 inorder to connect an external current source to the second electrodelayer 140. Meanwhile, the second semiconductor layer 150, the activelayer 160, and the first semiconductor layer 170, which will bedescribed later, are not formed on the exposed region 145. Further, theexposed region 145, as shown in FIG. 3, may be formed at the corners ofthe semiconductor light emitting device 100 in order to maximize a lightemitting area of the semiconductor light emitting device 100.

Meanwhile, the second electrode layer 140 may be formed of a materialincluding any one of Ag, Al, Pt, Ni, Pt, Pd, Au, Ir and a transparentconductive oxide. This is because the second electrode layer 140 may beformed as a layer, a characteristic of which is the minimization ofcontact resistance with the second semiconductor layer 150, since thesecond electrode layer 140 is in electrical contact with the secondsemiconductor layer 150, and has a function of improving luminousefficiency by reflecting light generated from the active layer 160outward.

The second semiconductor layer 150 is formed on the second electrodelayer 140. The active layer 160 is formed on the second semiconductorlayer 150. The first semiconductor layer 170 is formed on the activelayer 160.

Here, the first semiconductor layer 170 may be an n-type nitridesemiconductor and the second semiconductor layer 150 may be a p-typenitride semiconductor.

Meanwhile, the active layer 160 may be formed by selecting differentmaterials according to materials of which the first and secondsemiconductor layers 170 and 150 are formed. That is, since the activelayer 160 is a layer in which energy generated by the recombination ofelectrons and holes is converted into light and the light is emitted,the active layer 160 may be formed of a material having a smaller energyband gap than those of the first semiconductor layer 170 and the secondsemiconductor layer 150.

FIG. 8 illustrates a modification of the semiconductor light emittingdevice of FIG. 4. A semiconductor light emitting device 100′ of FIG. 8has the same structure as that of FIG. 4, except that it has passivationlayers 191 formed on the side surfaces of a light emitting structureincluding the second semiconductor layer 150, the active layer 160 andthe first semiconductor layer 170, and an unevenness formed on the topsurface of the first semiconductor layer 170. The passivation layer 191protects the light emitting structure, particularly the active layer160, from the outside. The passivation layer 191 may be formed of asilicon oxide and a silicon nitride such as SiO₂, SiO_(x)N_(y) andSi_(x)N_(y), and its thickness may be 0.1 μm to 2 μm. The active layer160, exposed outwardly, may function as a current leakage path duringthe operations of the semiconductor light emitting device 100′. Such aleakage may be prevented by forming the passivation layers 191 on theside surfaces of the light emitting structure. As shown in FIG. 8, whenunevenness is formed on the passivation layers 191, an improved lightextraction effect may be expected. Likewise, the unevenness may beformed on the top surface of the first semiconductor layer 170, andaccordingly, light incident in a direction of the active layer 160 maybe increasingly emitted outwards. Although not shown, when the lightemitting structure is etched in order to expose the second electrodelayer 140 in the manufacturing process, an etch stop layer may befurther formed on the second electrode layer 140 in order to prevent thematerial forming the second electrode layer 140 from adhering to theside surface of the active layer 160. The above-described modifiedembodiment of FIG. 8 may be applicable to an exemplary embodiment ofFIG. 9.

Meanwhile, the semiconductor light emitting device proposed in thepresent invention may have a structure modified in such a manner thatthe first electrode layer connected to the contact holes may be exposedoutwardly. FIG. 9 is a cross-sectional view illustrating a semiconductorlight emitting device according to another exemplary embodiment of thepresent invention. A semiconductor light emitting device 200 accordingto this embodiment may have a second semiconductor layer 250, an activelayer 260 and a first semiconductor layer 270 formed on a conductivesubstrate 210. In this case, a second electrode layer 240 may bedisposed between the second semiconductor layer 250 and the conductivesubstrate 210. Unlike the aforementioned embodiment, the secondelectrode layer 240 is not necessarily required. According to thisembodiment, contact holes 280 having contact regions 290 in contact withthe first semiconductor layer 270 are connected to a first electrodelayer 220. The first electrode layer 220 is exposed outwardly to have anelectrical connection portion 245. An electrode pad portion 247 may beformed on the electrical connection portion 245. The first electrodelayer 220 may be electrically separated from the active layer 260, thesecond semiconductor layer 250, the second electrode layer 240 and theconductive substrate 210 by an insulating layer 230. Unlike the contactholes connected to the conductive substrate in the aforementionedembodiment, the contact holes 280 according to this embodiment areelectrically separated from the conductive substrate 210, and the firstelectrode layer 220 connected to the contact holes 280 is exposedoutwardly. Accordingly, the conductive substrate 210 is electricallyconnected to the second semiconductor layer 240 and has a polaritydifferent from that of the aforementioned embodiment.

Hereinafter, an optimal state of the contact holes in terms of size andshape will be found through a simulation regarding changes in electricalcharacteristics according to a contact area between the first electrodelayer and the first semiconductor layer in the semiconductor lightemitting device proposed in the present invention. In this case, theresult of the simulation below may be applicable to the structures ofFIGS. 3 and 8. Also, the first and second semiconductor layers areformed of n-type and p-type semiconductor layers, respectively.

FIG. 5 is a graph illustrating n-type ohmic contact resistance andp-type ohmic contact resistance of a semiconductor light emitting devicehaving an area of 1,000×1,000 μm².

In the simulation of FIG. 5, n-type specific contact resistance, namely,specific contact resistance of the first electrode layer 120 and thecontact holes 180 is 10⁻⁴ ohm/cm² while p-type specific contactresistance, namely, specific contact resistance of the secondsemiconductor layer 150 and the second electrode layer 140 is 10⁻²ohm/cm².

Referring to FIG. 5, assuming that the semiconductor light emittingdevice 100 according to this embodiment of the invention is arectangular chip having a size of 1,000,000 μm², that is, a width whichis 1,000 μm and a height which is 1,000 μm, the resistance of thesemiconductor light emitting device 100 includes the first electrodelayer 120, the second electrode layer 140, the first semiconductor layer170, and the second semiconductor layer 150, contact resistance betweenthe second semiconductor layer 150 and the second electrode layer 140(hereinafter, referred to as “second contact resistance”), and contactresistance between the first semiconductor layer 170 and the firstelectrode layer 120 (hereinafter, referred to as “first contactresistance”), wherein major changes are made to the first contactresistance R1 and the second contact resistance R2 according to acontact area.

In particular, as shown in FIG. 5, as the contact area increases, morechange is made to the first contact resistance R1 as compared to thesecond contact resistance R2. Here, the X axis of FIG. 5 represents thesize of the contact area in which the first semiconductor layer 170 andthe first electrode layer 120 are in contact with each other, and the Yaxis of FIG. 5 represents contact resistance values. Therefore, thefigures of the X axis represent contact areas in which the firstsemiconductor layer 170 and the first electrode layer 120 are in contactwith each other. As for the contact area between the secondsemiconductor layer 150 and the second electrode layer 140, a valueobtained by subtracting a value of the X axis from the total area(1,000,000 μm²) of the semiconductor light emitting device 100corresponds to the contact area between the second semiconductor layer150 and the second electrode layer 140 which corresponds to the secondcontact resistance R2.

Here, the contact area between the first semiconductor layer 170 and thefirst electrode layer 120 indicates the total area of the contactregions 190 where the first electrode layer 120 and the firstsemiconductor layer 170 are in contact with each other through thecontact holes 180 as described with reference to FIGS. 3 and 4, i.e.,the sum total of areas of the contact regions 190 since there are aplurality of contact holes 180.

FIG. 6 is a graph illustrating the total resistance of the first contactresistance and the second contact resistance according to the contactarea between the first semiconductor layer and the first electrodelayer.

Referring to FIG. 6, since the first contact resistance R1 and thesecond contact resistance R2 of the semiconductor light emitting device100 according to this embodiment are connected to each other in series,the total resistance R3 obtained by adding the first contact resistanceR1 and the second contact resistance R2 among the resistances of thesemiconductor light emitting device 100 is most deeply influenced by thecontact area.

Here, as shown in FIG. 6, it is understood that as the contact area(referring to the values of the X axis) between the first semiconductorlayer 170 and the first electrode layer 120 increases, the totalresistance R3 (referring to the values of Y axis) rapidly decreases atan early stage, and as the contact area between the first semiconductorlayer 170 and the first electrode layer 120 further increases, the totalresistance R3 tends to increase.

Meanwhile, when the size of the semiconductor light emitting device 100is 1,000,000 μm², the n-type and p-type contact resistance of thesemiconductor light emitting device 100 is preferably below 1.6 ohm sothat the contact area between the first semiconductor layer 170 and thefirst electrode layer 120 is approximately 30,000 μm² to 250,000 μm².

A semiconductor light emitting device usually operates at an operationvoltage of 3.0 V to 3.2 V and at an operation current of approximately0.35 A. If the total resistance of the semiconductor light emittingdevice is approximately 2 ohm, the voltage becomes 0.70 V according tothe Equation of 0.35 A×2 ohm=0.70 V, which is beyond the common range of2.8 V to 3.8 V. When the voltage is beyond the range, modifications ofcircuit configuration may be required, and also heat and light outputdegradation may occur due to an increase in input power. Therefore, thetotal resistance of the semiconductor light emitting device ispreferably below 2 ohm, and since the sum of n-type and p-type contactresistance corresponds to approximately 80% of the total resistance, areference contact resistance is 1.6 ohm derived from the Equation of 2ohm×0.8=1.6 ohm.

That is, in the semiconductor light emitting device 100 as describedwith reference to FIGS. 3 and 4, it is most preferable in terms ofcontact resistance that the total contact area of the contact regions190 where the first electrode layer 120 and the first semiconductorlayer 170 are in contact with each other through the contact holes 180be approximately 30,000 μm² to 250,000 μm².

FIG. 7 is a graph illustrating luminous efficiency according to thecontact area between the first semiconductor layer and the firstelectrode layer.

As described with reference to FIG. 6, when the contact area between thefirst semiconductor layer 170 and the first electrode layer 120 is30,000 μm² to 250,000 μm², the total resistance is low, and accordingly,the luminous efficiency of the semiconductor light emitting device 100is likely to be high. However, it is not considered that as the contactarea between the first semiconductor layer 170 and the first electrodelayer 120 increases, a light emitting area of the semiconductor lightemitting device 100 is practically reduced.

That is, as shown in FIG. 7, the luminous efficiency of thesemiconductor light emitting device 100 increases by reducing the totalresistance until the contact area between the first semiconductor layer170 and the first electrode layer 120 is 70,000 μm². However, when thecontact area between the first semiconductor layer 170 and the firstelectrode layer 120 continuously increases above 70,000 μm², luminousefficiency becomes lower. An increase in the contact area between thefirst semiconductor layer 170 and the first electrode layer 120indicates a decrease in the contact area between the secondsemiconductor layer 150 and the second electrode layer 140, whichreduces a light-emitting amount of the semiconductor light emittingdevice 100.

Therefore, the contact area between the first semiconductor layer 170and the first electrode layer 120 needs to be appropriately determined,that is, the contact area between the first semiconductor layer 170 andthe first electrode layer 120 is preferably below 130,000 μm² so thatthe level of luminous efficiency is above 90% as shown in FIG. 7.

As a result, in the semiconductor light emitting device 100 according tothis embodiment, it is most preferable that the contact area between thefirst semiconductor layer 170 and the first electrode layer 120 throughthe contact holes 180 be 30,000 μm² to 130,000 μm². Since thesemiconductor light emitting device 100 corresponds to a case where thechip size is 1,000,000 μm², a contact area between the first electrodelayer 120 and the first semiconductor layer 170 that is 3% to 13% of thetotal area of the semiconductor light emitting device 100, is the mostproper amount of contact area.

Meanwhile, when the number of the contact holes 180 is very small, thecontact area between the first semiconductor layer 170 and the firstelectrode layer 120 for each of the contact regions 190 between thefirst semiconductor layer 170 and the first electrode layer 120increases, and accordingly, the area of the first semiconductor layer170 to which current needs to be supplied increases, and the amount ofcurrent which should be supplied to the contact regions 190 alsoincreases. This causes a current-crowding effect at the contact regions190 between the first semiconductor layer 170 and the first electrodelayer 120.

In addition, when the number of the contact holes 180 is very large, thesize of each of the contact holes 180 necessarily becomes very small,thereby causing difficulty in the manufacturing process.

The number of the contact holes 180 may therefore be properly selectedaccording to the size of the semiconductor light emitting device 100,i.e., the chip size. When the size of the semiconductor light emittingdevice 100 is 1,000,000 μm², the number of the contact holes 180 may be5 to 50.

Meanwhile, when the plurality of contact holes 180 of the semiconductorlight emitting device 100 are formed, the contact holes 180 may beuniformly arranged. In order to uniformly spread current, since thefirst semiconductor layer 170 and the first electrode layer 120 are incontact with each other through the contact holes 180, the contact holes180, i.e., the contact regions 190 between the first semiconductor layer170 and the first electrode layer 120 may be uniformly arranged.

Here, when the size of the semiconductor light emitting device 100 is1,000,000 μm² and the number of the contact holes 180 is 5 to 50,separation distances between adjacent contact holes among the pluralityof contact holes may be 100 μm to 400 μm, in order to uniformly arrangethe semiconductor light emitting device 100. The separation distancesare values measured by connecting central points of the adjacent contactholes.

Meanwhile, the semiconductor light emitting device 100 is capable ofachieving uniform current spreading by uniformly arranging the pluralityof contact holes 180. Contrary to a semiconductor light emitting devicehaving a size of 1,000,000 μm², which conventionally operates atapproximately 350 mA, the semiconductor light emitting device 100according to this embodiment of the invention operates stably anddecreases the current crowding effect even though a high current ofapproximately 2 A is applied, resulting in the semiconductor lightemitting device with improved reliability.

FIGS. 10 and 11 illustrate the result of a simulation conducted bychanging n-type specific contact resistance. In this simulation, then-type specific contact resistance is 10⁻⁶ ohm/cm² and p-type specificcontact resistance is 10⁻² ohm/cm². The n-type specific contactresistance is influenced by the doping levels of the n-typesemiconductor layer, n-type electrode materials, and heat treatmentmethods. Therefore, the n-type specific contact resistance may bereduced by up to 10⁻⁶ ohm/cm² by increasing the doping concentration ofthe n-type semiconductor layer or adopting metal having a low energybarrier such as Al, Ti and Cr as an n-type electrode material. That is,the n-type specific contact resistance may be commonly 10⁻⁴ ohm/cm² to10⁻⁶ ohm/cm².

Referring to FIG. 10, the sum total of the n-type and p-type specificcontact resistance, namely, the total contact resistance R4 may bemaintained at a very low level even in a smaller contact area, ascompared with the result shown in FIG. 6. Also, as a result of reviewingluminous efficiency according to the contact area with reference to FIG.11, luminous efficiency may be maintained at a high level even in asmaller contact area, as compared with the result shown in FIG. 7. Inthis case, the value of luminous efficiency above 100% indicates a valuerelative to the result shown in FIG. 7. Referring to the result of thesimulation shown in FIGS. 10 and 11, the condition that the totalcontact resistance is below 1.6 ohm and the luminous efficiency is above90% is when the contact area between the first electrode layer and thefirst semiconductor layer is 6150 μm² to 156,800 μm² per 1,000,000 μm²area.

When the number of contact holes is determined on the basis of such aresult, the contents described with reference to the result of theprevious simulation may be applied. Specifically, in the case ofcircular contact holes having a radius of approximately 1 μm to 50 μm,approximately 1 to 48,000 contact holes are required to satisfy theabove condition. Further, assuming that the contact holes are uniformlyarranged, the distance between two adjacent contact holes should beapproximately 5 μm to 500 μm.

Hereinafter, a semiconductor light emitting device according to anotherexemplary embodiment of the present invention will be described througha variety of embodiments.

First, a semiconductor light emitting device according to anotherexemplary embodiment of the invention will be described with referenceto FIGS. 12 through 16.

A semiconductor light emitting device 300 according to another exemplaryembodiment of the invention includes a conductive substrate 340, a firstconductivity type semiconductor layer 330, an active layer 320 and asecond conductivity type semiconductor layer 310 that are sequentiallystacked. This semiconductor light emitting device 300 includes a firstelectrode layer 360 formed between the conductive substrate 340 and thefirst conductivity type semiconductor layer 330, and a second electrodepart 350 including an electrode pad portion 350-b, an electrodeextension portion 350-a, and an electrode connection portion 350-c.

The electrode pad portion 350-b extends from the first electrode layer360 to the surface of the second conductivity type semiconductor layer310 and is electrically separated from the first electrode layer 360,the first conductivity type semiconductor layer 330, and the activelayer 320. The electrode extension portion 350-a extends from the firstelectrode layer 360 to the inside of the second conductivity typesemiconductor layer 310 and is electrically separated from the firstelectrode layer 360, the first conductivity type semiconductor layer330, and the active layer 320. The electrode connection portion 350-c isformed in the same layer as the first electrode layer 360, but iselectrically separated from the first electrode layer 360. The electrodeconnection portion 350-c connects the electrode pad portion 350-b to theelectrode extension portion 350-a.

The conductive substrate 340 may be a metallic substrate or asemiconductor substrate. When the conductive substrate 340 is themetallic substrate, the conductive substrate 340 may be formed of anyone of Au, Ni, Cu, and W. Also, when the conductive substrate 340 is thesemiconductor substrate, the conductive substrate 340 may be formed ofany one of Si, Ge, and GaAs. Examples of a method of forming aconductive substrate in a semiconductor light emitting device include aplating method of forming a plating seed layer to form a substrate and asubstrate bonding method of separately preparing a conductive substrateand bonding the conductive substrate by using a conductive adhesive,such as Au, Au—Sn, and Pb—Sr.

Each of the semiconductor layers 330 and 310 may be formed of aninorganic semiconductor such as a GaN-based semiconductor, a ZnO-basedsemiconductor, a GaAs-based semiconductor, a GaP-based semiconductor,and a GaAsP-based semiconductor. The semiconductor layers may be formedby using, for example, molecular beam epitaxy (MBE). In addition, thesemiconductor layers may be formed of any one of semiconductors, such asa group III-V semiconductor, a group II-VI semiconductor and Si.

The active layer 320 is a layer where light emission is activated. Theactive layer 320 may be formed of a material having a smaller energyband gap than each of the first and second conductivity typesemiconductor layers 330 and 310. For example, when the first and secondconductivity type semiconductor layers 330 and 310 may be a GaN-basedcompound semiconductor, the active layer 320 may be formed by using anInAlGaN-based compound semiconductor that has a smaller energy bandgapthan GaN. That is, the active layer 320 may be In_(x)Al_(y)Ga_((1-x-y))N(where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1 are satisfied).

Here, in consideration of the characteristics of the active layer 320,the active layer 320 is preferably not doped with impurities. Awavelength of emitted light may be controlled by adjusting a mole ratioof constituents. Therefore, the semiconductor light emitting device 300may emit any one of infrared light, visible light, and UV lightaccording to the characteristics of the active layer 320.

An energy well structure appears in the entire energy band diagram ofthe semiconductor light emitting device 300 according to the activelayer 320. Electrons and holes from each of the semiconductor layers 330and 310 are moving and are trapped within the energy well structure,which results in higher luminous efficiency.

The first electrode layer 360 electrically connects the firstconductivity type semiconductor layer 330 to an external current source(not shown). The first electrode layer 360 may be formed of metal. Forexample, the first electrode layer 360 may be formed of Ti as an n-typeelectrode, and Pd or Au as a p-type electrode.

The first electrode layer 360 may reflect light generated from theactive layer 320. The reflected light is directed to a light emittingsurface, and accordingly, the luminous efficiency of the semiconductorlight emitting device 300 is improved. In order to reflect the lightgenerated from the active layer 320, the first electrode layer 360 maybe formed of metal that appears white in a visible light region. Forexample, the white metal may be any one of Ag, Al, and Pt. The firstelectrode layer 360 will be further described with reference to FIGS.14A through 14C.

The second electrode part 350 electrically connects the secondconductivity type semiconductor layer 310 to an external current source(not shown). The second electrode part 350 may be formed of metal. Forexample, the second electrode part 350 may be formed of Ti as an n-typeelectrode, and Pd or Au as a p-type electrode. Particularly, the secondelectrode part 350 according to this embodiment includes the electrodepad portion 350-b, the electrode extension portion 350-a, and theelectrode connection portion 350-c.

Referring to FIG. 13A, the electrode pad portion 350-b is formed on thesurface of the second conductivity type semiconductor layer 310, and theplurality of electrode extension portions 350-a, indicated by a dottedline, are located inside the second conductivity type semiconductorlayer 310.

In FIG. 13B, the top surface of the second conductivity typesemiconductor layer 310 shown in FIG. 13A is taken along lines A-A′,B-B′, and C-C′. The line A-A′ is taken to show a section that onlyincludes the electrode extension portion 350-a. The line B-B′ is takento show a section that includes the electrode pad portion 350-b and theelectrode extension portion 350-a. The line C-C′ is taken to show asection that includes neither the electrode extension portion 350-a northe electrode pad portion 350-b.

FIGS. 14A through 14C are cross-sectional views of the semiconductorlight emitting device shown in FIG. 13B taken along lines A-A′, B-B′,and C-C′. Hereinafter, a detailed description will be made withreference to FIGS. 12, 13A, 13B, and 14A through 14C.

In FIG. 14A, the electrode extension portion 350-a extends from thefirst electrode layer 360 to the inside of the second conductivity typesemiconductor layer 310. The electrode extension portion 350-a passesthrough the first conductivity type semiconductor layer 330 and theactive layer 320 and extends to the second conductivity typesemiconductor layer 310. The electrode extension portion 350-a extendsat least to part of the second conductivity type semiconductor layer310. However, the electrode extension portion 350-a does not necessarilyextend to the surface of the second conductivity type semiconductorlayer 310. This is because the electrode extension portion 350-a is usedto spread current in the second conductivity type semiconductor layer310.

The electrode extension portion 350-a needs to have a predetermined areato spread the current in the second conductivity type semiconductorlayer 310. Contrary to the electrode pad portion 350-b, the electrodeextension portion 350-a is not used for the electrical connection.Therefore, the electrode extension portion 350-a is formed by apredetermined number so that each electrode extension portion 350-a hasan area small enough to allow uniform current spreading in the secondconductivity type semiconductor layer 310. A small number of electrodeextension portions 350-a may cause deterioration in electricalcharacteristics due to non-uniform current spreading. A large number ofelectrode extension portions 350-a may cause difficulty in the processof forming the electrode extension portions 350-a and a decrease in alight emitting area due to a decrease in the area of the active layer.Therefore, the number of electrode extension portions 350-a may beappropriately determined in consideration of these facts. Each of theelectrode extension portions 350-a is formed to have as small an area aspossible and allows for uniform current spreading.

The plurality of electrode extension portions 350-a may be formed forcurrent spreading. Also, the electrode extension portion 350-a may havea cylindrical shape. A cross section of the electrode extension portion350-a may be smaller than that of the electrode pad portion 350-b.Further, the electrode extension portions 350-a may be separated fromthe electrode pad portion 350-b by a predetermined distance. Theelectrode extension portions 350-a and the electrode pad portion 350-bmay be connected to each other in the first electrode layer 360 by theelectrode connection portion 350-c to be described below. For thisreason, the electrode extension portions 350-a are separated from theelectrode pad portion 350-b by the predetermined distance, and thusinduce uniform current spreading.

The electrode extension portions 350-a are formed from the firstelectrode layer 360 to the inside of the second conductivity typesemiconductor layer 310. Since the electrode extension portions 350-aare used for current spreading in the second conductivity typesemiconductor layer 310, the electrode extension portions 350-a need tobe electrically separated from the other layers. Accordingly, theelectrode extension portions 350-a are electrically separated from thefirst electrode layer 360, the first conductivity type semiconductorlayer 330, and the active layer 320. Electrical separation may beachieved by using an insulating material such as a dielectric.

In FIG. 14B, the electrode pad portion 350-b extends from the firstelectrode layer 360 to the surface of the second conductivity typesemiconductor layer 310. The electrode pad portion 350-b starts from thefirst electrode layer 360, passes through the first conductivity typesemiconductor layer 330, the active layer 320 and the secondconductivity type semiconductor layer 310, and extends to the surface ofthe second conductivity type semiconductor layer 310. Since theelectrode pad portion 350-b is formed to connect the second electrodepart 350 to the external current source, at least one electrode padportion 350-b needs to be included.

The electrode pad portion 350-b extends from the first electrode layer360 to the surface of the second conductivity type semiconductor layer310. Since the electrode pad portion 350-b is electrically connected tothe external current source at the surface of the second conductivitytype semiconductor layer 310 to supply current to the electrodeextension portions 350-a, the electrode pad portion 350-b may beelectrically separated from the first electrode layer 360, the firstconductivity type semiconductor layer 330, and the active layer 320.Electrical separation may be achieved by using an insulating materialsuch as a dielectric.

The electrode pad portion 350-b supplies the current to the electrodeextension portions 350-a. Further, the electrode pad portion 350-b maybe formed so that the electrode pad portion 350-b is not electricallyseparated from the second conductivity type semiconductor layer 310 soas to directly spread the current. The electrode pad portion 350-b maybe electrically separated from the second conductivity typesemiconductor layer 310 or not, according to whether current supply tothe electrode extension portions 350-a or current spreading in thesecond conductivity type semiconductor layer 310 is required.

A cross section of the electrode pad portion 350-b at the active layer320 may be smaller than that of the electrode pad portion 350-b at thesurface of second conductivity type semiconductor layer 310. In thisway, the area of the active layer 320 is maximized as much as possiblein order to ensure an increase in luminous efficiency. However, theelectrode pad portion 350-b at the surface of the second conductivitytype semiconductor layer 310 needs to have a predetermined area so as tobe connected with the external current source.

The electrode pad portion 350-b may be located at the center of thesemiconductor light emitting device 300. In this case, the electrodeextension portions 350-a are preferably separated from the electrode padportion 350-b by the predetermined distance, and uniformly distributed.Referring to FIG. 13A, the electrode pad portion 350-b and the electrodeextension portions 350-a are uniformly distributed over the secondconductivity type semiconductor layer 310 to optimize the currentspreading. In FIG. 13A, it is assumed that there are one electrode padportion 350-b and twelve electrode extension portions 350-a. However,the number of electrode pad portion 350-b and the number of electrodeextension portions 350-a may be appropriately determined inconsiderations of factors for electrical connection state (e.g. theposition of the external current source) and current spreading state(e.g. the thickness of the second conductivity type semiconductor layer310).

When the plurality of electrode extension portions 350-a are formed, theelectrode pad portion 350-b may be directly connected to each of theplurality of electrode extension portions 350-a. In this case, theelectrode pad portion 350-b is formed at the center of the semiconductorlight emitting device 300, and the electrode extension portions 350-aare formed around the electrode pad portion 350-b. Further, theelectrode connection portion 350-c may directly connect the electrodepad portion 350-b and the electrode extension portions 350-a in a radialdirection.

Alternatively, some of the plurality of electrode extension portions350-a may be directly connected to the electrode pad portion 350-b.Other electrode extension portions 350-a may be connected to theelectrode extension portions 350-a that are directly connected to theelectrode pad portion 350-b, such that these electrode extensionportions 350-a are indirectly connected to the electrode pad portion350-b. In this way, a larger number of electrode extension portions350-a can be formed to thereby increase current spreading efficiency.

In FIGS. 14A through 14C, the electrode connection portion 350-c isformed in the first electrode layer 360 and connects the electrode padportion 350-b and the electrode extension portions 350-a to each other.Therefore, a considerable amount of the second electrode part 350 islocated at a rear surface opposite to the direction in which light isemitted from the active layer 320, thereby increasing luminousefficiency. Particularly, in FIG. 14C, only the electrode connectionportion 350-c is located in the first electrode layer 360. The secondelectrode part 350 is not located at the first conductivity typesemiconductor layer 330, the active layer 320, and the secondconductivity type semiconductor layer 310. Accordingly, as shown in FIG.14C, the electrode pad portion 350-b and the electrode connectionportions 350-a do not affect light emissions, so they have higherluminous efficiency. Although not shown in FIG. 14C, the first electrodelayer 360 may be in contact with the conductive substrate 340 to therebybe connected to the external current source.

The electrode connection portion 350-c is electrically separated fromthe first electrode layer 360. The first electrode layer 360 and thesecond electrode part 350 include electrodes that have polaritiesopposite to each other to supply external power to the firstconductivity type semiconductor layer 330 and the second conductivitytype semiconductor layer 310, respectively. Therefore, the twoelectrodes must be electrically separated from each other. Electricalseparation may be achieved by using an insulating material, such as adielectric.

In FIG. 14B, since the electrode pad portion 350-b is located on thesurface of the second conductivity type semiconductor layer 310, it ispossible to obtain characteristics of a vertical semiconductor lightemitting device. In FIG. 14C, since the electrode connection portion350-c is located in the same plane as the first electrode layer 360, itis possible to obtain the characteristics of a horizontal semiconductorlight emitting device. Therefore, the semiconductor light emittingdevice 300 has a structure in which the horizontal semiconductor lightemitting device and the vertical semiconductor light emitting device areintegrated.

Referring to FIGS. 14A through 14C, the second conductivity typesemiconductor layer 310 may be an n-type semiconductor layer, and thesecond electrode part 350 may be an n-type electrode part. In this case,the first conductivity type semiconductor layer 330 may be a p-typesemiconductor layer, and the first electrode layer 360 may be a p-typeelectrode. The second electrode part 350 includes the electrode padportion 350-b, the electrode extension portions 350-a, and the electrodeconnection portion 350-c that are connected to each other. When thesecond electrode part 350 is formed of the n-type electrode, the secondelectrode part 350 may be electrically separated from the firstelectrode layer 360 formed of the p-type electrode by an insulating part370 that is formed of an insulating material.

FIG. 15A illustrates the light emission of a semiconductor lightemitting device having an uneven pattern formed on the surface thereofaccording to a modified embodiment of this embodiment. FIG. 15Billustrates the current spreading of a semiconductor light emittingdevice having an uneven pattern formed on the surface thereof accordingto another modified embodiment of this embodiment.

The semiconductor light emitting device 300 according to this embodimentincludes the second conductivity type semiconductor layer 310 that formsan outermost surface in a direction in which emitted light moves.Accordingly, it is easy to form an uneven pattern on the surface byusing a method well-known in the art, such as photolithography. In thiscase, light emitted from the active layer 320 passes through an unevenpattern 380 that is formed on the surface of the second conductivitytype semiconductor layer 310, and then the light is extracted. Theuneven pattern 380 increases light extraction efficiency.

The uneven pattern 380 may have a photonic crystal structure. Photoniccrystals contain different media with different refractivity in whichthe media are regularly arranged in a crystal-like manner. The photoniccrystals may increase light extraction efficiency by controlling lightin unit of length corresponding to a multiple of a wavelength of light.The photonic crystal structure may be formed according to an appropriateprocess after forming the second conductivity type semiconductor layer310 and the second electrode part 350. For example, the photonic crystalstructure may be formed through an etching process.

Even though the uneven pattern 380 is formed on the second conductivitytype semiconductor layer 310, current spreading is not affected by theuneven pattern 380. Referring to FIG. 15B, the current spreading in theelectrode extension portions 350-a is not affected by the uneven pattern380. Each of the electrode extension portions 350-a spreads currentbelow the uneven pattern 380 and the uneven pattern 380 extracts emittedlight, thereby increasing luminous efficiency.

FIG. 16 is a graph illustrating the relationship between the currentdensity and luminous efficiency of a light emitting surface. Whencurrent density is above approximately 10 A/cm² in the graph, a smallerlevel of current density indicates higher luminous efficiency and alarger level of current density indicates lower luminous efficiency.

Table 1 below shows values related thereto.

TABLE 1 Light Emitting Current Density Luminous Improvement Area (cm²)(A/cm²) Efficiency (lm/W) Rate (%) 0.0056 62.5 46.9 100 0.0070 50.0 51.5110 0.0075 46.7 52.9 113 0.0080 43.8 54.1 115

As the light emitting area increases, luminous efficiency improves.However, in order to ensure the light emitting area, it is necessary todecrease the area of distributed electrodes, and accordingly, thecurrent density of the light emitting surface tends to decrease. Such adecrease in the current density of the light emitting surface maydeteriorate the electrical characteristics of the semiconductor lightemitting device.

This problem may be solved by ensuring current spreading by using theelectrode extension portions. That is, the problem of the electricalcharacteristics that may caused by the decrease in the current densitymay be addressed by forming the electrode extension portions in such amanner that the electrode extension portions are formed inside the lightemitting device without extending to the light emitting surface andserve to spread current therein. Therefore, the semiconductor lightemitting device according to this embodiment is capable of achievingdesired current spreading and obtaining a maximum light emitting area,thereby improving luminous efficiency.

A semiconductor light emitting device according to another exemplaryembodiment of the present invention will be described with reference toFIGS. 17 through 20.

FIG. 17 is a perspective view illustrating a light emitting deviceaccording to another exemplary embodiment of the present invention.FIGS. 18A and 18B are top views illustrating the light emitting deviceof FIG. 17. FIGS. 19A through 19C are cross-sectional views illustratingthe light emitting device of FIG. 18B, taken along lines A-A′, B-B′, andC-C′, respectively.

A light emitting device 400 according to another exemplary embodiment ofthe invention includes a light emitting stack 430, 420 and 410, at leastone barrier portion 470, a second electrode structure 460, a firstelectrode structure 440, and a conductive substrate 450. The lightemitting stack 430, 420 and 410 includes first and second conductivitytype semiconductor layers 430 and 410, and an active layer 420 formedtherebetween, and has a first surface and a second surface opposite toeach other and provided as the first and second conductivity typesemiconductor layers 430 and 410. The barrier portion 470 has electricalinsulation and extends from the second surface of the light emittingstack 430, 420 and 410 to at least part of the second conductivity typesemiconductor layer 410 to divide the light emitting stack 430, 420 and410 into a plurality of light emitting regions. The second electrodestructure 460 is connected to the second conductivity type semiconductorlayer 410 that is located at the plurality of light emitting regions.The first electrode structure 440 is formed on the second surface of thelight emitting stack 430, 420 and 410 so as to be connected to the firstconductivity type semiconductor layer 430. The conductive substrate 450is formed on the second surface of the light emitting stack 430, 420 and410 so as to be electrically connected to the first electrode structure440.

The light emitting stack 430, 420 and 410 includes the first and secondconductivity type semiconductor layers 430 and 410, and the active layer420 formed therebetween. The light emitting stack 430, 420 and 410 hasan outer surface of the second conductivity type semiconductor layer 410that serves as the first surface and an outer surface of the firstconductivity type semiconductor layer 430 that serves as the secondsurface.

Each of the semiconductor layers 430 and 410 may be formed of asemiconductor, such as a GaN-based semiconductor, a ZnO-basedsemiconductor, a GaAs-based semiconductor, a GaP-based semiconductor,and a GaAsP-based semiconductor. The semiconductor layer may be formedby using, for example, molecular beam epitaxy (MBE). In addition, eachof the semiconductor layers may be formed of any one of semiconductors,such as a group III-V semiconductor, a group II-VI semiconductor, andSi. The light emitting stack may grow on a non-conductive substrate (notshown), such as a sapphire substrate, having relatively smalllattice-mismatching. The non-conductive substrate is removed laterbefore a conductive substrate is bonded.

The active layer 420 is a layer in which light emission is activated.The active layer 420 is formed of a material that has a smaller energybandgap than each of the second and first conductivity typesemiconductor layers 410 and 430. For example, when each of the secondand first conductivity type semiconductor layers 410 and 430 is formedof a GaN-based compound semiconductor, the active layer 420 may beformed by using an InAlGaN-based compound semiconductor that has asmaller energy bandgap than GaN. That is, the active layer 420 mayinclude In_(x)Al_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1 aresatisfied).

Here, in consideration of the characteristics of the active layer 420,the active layer 420 is preferably not doped with impurities. Awavelength of emitted light may be controlled by adjusting a mole ratioof constituents. Therefore, the light emitting device 400 may emit anyone of infrared light, visible light, and UV light according to thecharacteristics of the active layer 420.

An energy well structure appears in the entire energy band diagram ofthe light emitting device 400 according to the active layer 420.Electrons and holes from each of the semiconductor layers 430 and 410are moving and are trapped within the energy well structure, whichresults in higher luminous efficiency.

The barrier portion 470 extends from the second surface of the lightemitting stack 430, 420, and 410 to at least part of the secondconductivity type semiconductor layer 410, such that the light emittingstack 430, 420, and 410 is divided into the plurality of light emittingregions. The barrier portion 470 divides the second conductivity typesemiconductor layer 410 into a plurality of regions. When a separatingunit, such as a laser, is used between the second conductivity typesemiconductor layer 410 and a substrate for growth (not shown) formed onthe second conductivity type semiconductor layer 410, the barrierportion 470 reduces stress that is generated due to heat energy appliedto the interface therebetween.

For example, when a laser is used as the separating unit for separatingthe second conductivity type semiconductor layer 410 from the substratefor growth, the temperature at the interface is approximately 1000° C.Heat energy from the laser separates the second conductivity typesemiconductor layer 410 from the substrate for growth. However, the heatgenerates stress that induces contraction and expansion of thesemiconductor layers and the conductive substrate 450 to be bondedlater. In general, since the magnitude of stress is in proportion to thearea, the stress may adversely affect a large area light limitingdevice.

However, since the light emitting device 400 according to thisembodiment includes the barrier portion 470, the area of the secondconductivity type semiconductor layer 410 is divided into a plurality ofsmaller areas of the plurality of light emitting regions to therebyreduce stress. That is, expansion and contraction are more easilyperformed according to the plurality of light emitting regions, suchthat light emission of the light emitting stack 430, 420, and 410 can bestabilized.

Preferably, the barrier portion 470 electrically insulates thesemiconductor layers 430 and 410, and the active layer 420. To do so,the barrier portion 470 may be filled with air. Alternatively, thebarrier portion 470 may have an insulating layer formed therein, inwhich the insulating layer is filled with air. Further, the entirebarrier portion may be filled with an insulating material, such as adielectric, to achieve electrical insulation.

In order to electrically insulate the light emitting stack 430 and 410,the barrier portion 470 may extend from the second surface to the topsurface of the second conductivity type semiconductor layer 410.However, the barrier portion 470 does not necessarily extend to the topsurface of the second conductivity type semiconductor layer 410. Thebarrier portion 470 may extend to the inside of the second conductivitytype semiconductor layer 410.

Also, the barrier portion 470 may have a single structure.Alternatively, the barrier portion 470 may include a plurality ofbarriers that are separated from each other. In this case, the pluralityof barriers may appear different from each other in order to allowrequired electrical insulating characteristics. For example, the barrierthat surrounds a bonding portion 461 and the barrier that surrounds acontact hole 462 may be different in height and shape.

The second electrode structure 460 is connected to the secondconductivity type semiconductor layer 410 located at the plurality oflight emitting regions that are separated from each other by the barrierportion 470. The second electrode structure 460 includes the contacthole 462, the bonding portion 461, and a wiring portion 463.

There may be a plurality of contact holes 462. Each of the plurality ofcontact holes 462 may be formed in each of the plurality of lightemitting regions. A single contact hole may be formed in a single lightemitting region or a plurality of contact holes may be formed in asingle light emitting region. While the contact holes 462 areelectrically connected to the second conductivity type semiconductorlayer 410, the contact holes 462 are electrically insulated from thefirst conductivity type semiconductor layer 430 and the active layer420. To do so, the contact hole 462 extends from the second surface ofthe light emitting stack 430, 420, and 410 to at least part of thesecond conductivity type semiconductor layer 410. The contact holes 462are formed to spread current in the second conductivity typesemiconductor layer 410.

The bonding portion 461 is connected from the first surface of the lightemitting stack 430, 420, and 410 to at least one of the plurality ofcontact holes 462. A region that is exposed at the first surface isprovided as a bonding region.

The wiring portion 463 is formed at the second surface of the lightemitting stack 430, 420, and 410. While the wiring portion 463 iselectrically insulated from at least the first conductivity typesemiconductor layer 430, the wiring portion 463 electrically connectsone contact hole 462, which is connected to the bonding portion 461, andanother contact hole 462. Also, the wiring portion 463 may connect thecontact holes 462 to the bonding portion 461. The wiring portion 463 islocated below the second conductivity type semiconductor layer 410 andthe active layer 420 to thereby increase luminous efficiency.

Hereinafter, the contact holes 462, the bonding portion 461, and thewiring portion 463 will be described in more detail with reference toFIGS. 18A through 19C.

The first electrode structure 440 is formed on the second surface of thelight emitting stack 430, 420, and 410 so as to be electricallyconnected to the first conductivity type semiconductor layer 430. Thatis, the first electrode structure 440 has an electrode that electricallyconnects the first conductivity type semiconductor layer 430 to anexternal current source (not shown). The first electrode structure 440may be formed of metal. For example, the first electrode structure 440may be formed of Ti as an n-type electrode, and Pd or Au as a p-typeelectrode.

The first electrode structure 440 may reflect light generated from theactive layer 420. Since the first electrode structure 440 is locatedbelow the active layer 420, the first electrode structure 440 is locatedat a surface opposite to a direction, in which the light emitting deviceemits light, on the basis of the active layer 420. Light moving from theactive layer 420 to the first electrode structure 440 is opposite to thelight emitting direction, and thus the light needs to be reflected toincrease luminous efficiency. Therefore, the light reflected by thefirst electrode structure 440 moves toward a light emitting surface,thereby increasing the luminous efficiency of the light emitting device.

In order to reflect the light generated from the active layer 420, thefirst electrode structure 440 may be formed of metal that appears whitein the visible light region. For example, the white metal may be any oneof Ag, Al, and Pt. The first electrode structure 440 will be describedbelow in more detail with reference to FIGS. 19A through 19C.

The conductive substrate 450 is formed on the second surface of thelight emitting stack 430, 420, and 410 so as to be electricallyconnected to the first electrode structure 440. The conductive substrate450 may be a metallic substrate or a semiconductor substrate. When theconductive substrate 450 is the metallic substrate, the conductivesubstrate 450 may be formed of any one of Au, Ni, Cu, and W. Further,when the conductive substrate 450 is the semiconductor substrate, theconductive substrate 450 may be formed of any one of Si, Ge, and GaAs.Examples of a method of forming a conductive substrate in a lightemitting device include a plating method of forming a plating seed layerto form a substrate and a substrate bonding method of separatelypreparing a conductive substrate and bonding the conductive substrate byusing a conductive adhesive, such as Au, Au—Sn, and Pb—Sr.

Referring to FIG. 18A, the bonding portion 461 is formed on the surfaceof the second conductivity type semiconductor layer 410, and theplurality of contact holes 462, indicated by a dotted line, are locatedinside the second conductivity type semiconductor layer 410. The secondconductivity type semiconductor layer 410 includes the plurality oflight emitting regions that are separated from each other by the barrierportion 470. In FIGS. 18A and 18B, only one bonding portion 461 isshown. However, a plurality of bonding portions may be formed on thesame light emitting region or a plurality of bonding portions may beformed on each of the plurality of light emitting regions. Further, eachof the contact holes 462 is formed in each of the light emittingregions. However, the plurality of contact holes 462 may be formed in asingle light emitting region to thereby improve current spreading.

In FIG. 18B, the top surface of the second conductivity typesemiconductor layer 410 shown in FIG. 18A is taken along lines A-A′,B-B′, and C-C′. The line A-A′ is taken to show a section that onlyincludes the contact holes 462. The line B-B′ is taken to show a sectionthat includes the bonding portion 461 and the contact holes 462. Theline C-C′ is taken to show a section that only includes the wiringportion 463 and does not include the contact holes 462 and the bondingportion 461.

FIGS. 19A through 19C are cross-sectional views illustrating the lightemitting device of FIG. 18B taken along lines A-A′, B-B′, and C-C′.Hereinafter, a detailed description will be made with reference to FIGS.17, 18A, 18B, and 19A through 19C.

In FIG. 19A, each of the contact holes 462 extends from the firstelectrode layer 440 to the inside of the second conductivity typesemiconductor layer 410. The contact holes 462 pass through the firstconductivity type semiconductor layer 430 and the active layer 420 andextend to the second conductivity type semiconductor layer 410. Thecontact holes 462 extend at least to part of the second conductivitytype semiconductor layer 410. However, the contact holes 462 do notnecessarily extend to the surface of the second conductivity typesemiconductor layer 410. However, since the contact holes 462 are usedfor current spreading in the second conductivity type semiconductorlayer 410, the contact holes 462 need to extend to the secondconductivity type semiconductor layer 410.

The contact hole 462 needs to have a predetermined area to spread thecurrent in the second conductivity type semiconductor layer 410.Contrary to the bonding portion 461, the contact hole 462 is not usedfor an electrical connection. Therefore, the contact holes 462 areformed in a predetermined number so that each contact hole 462 has anarea small enough to allow for uniform current spreading in the secondconductivity type semiconductor layer 410. A small number of contactholes 462 may cause deterioration in electrical characteristics due tonon-uniform current spreading. A large number of contact holes 462 maycause difficulty in the process of forming the contact holes 462 and adecrease in a light emitting area due to a decrease in the area of theactive layer. Therefore, the number of contact holes 462 may beappropriately determined in considerations of these facts. Each of thecontact holes 462 is formed to have as small an area as possible andallow for uniform current spreading.

The plurality of contact holes 462 may be formed for current spreading.Also, the contact hole 462 may have a cylindrical shape. A cross sectionof the contact hole 462 may be smaller than that of the bonding portion461. Further, the contact hole 462 may be separated from the bondingportion 461 by a predetermined distance. The contact holes 462 and thebonding portion 461 may be connected to each other in the firstelectrode structure 440 by the wiring portion 463 to be described below.For this reason, the contact holes 462 are separated from the bondingportion 461 by the predetermined distance, and thus induce uniformcurrent spreading in the first conductivity type semiconductor layer430.

The contact holes 462 are formed from the first electrode structure 440to the inside of the second conductivity type semiconductor layer 410.Since the contact holes 462 are formed to spread the current in thesecond conductivity type semiconductor layer 410, the contact holes 462need to be electrically separated from the first conductivity typesemiconductor layer 430 and the active layer 420. Accordingly, thecontact holes 462 are electrically separated from the first electrodestructure 440, the first conductivity type semiconductor layer 430, andthe active layer 420. Electrical separation may be achieved by using aninsulating material such as a dielectric.

In FIG. 19B, the bonding portion 461 starts from the first electrodestructure 440, passes through the first conductivity type semiconductorlayer 430, the active layer 420 and the second conductivity typesemiconductor layer 410, and extends to the surface of the secondconductivity type semiconductor layer 410. Since the bonding portion 461is connected from the first surface of the light emitting stack 430,420, 410 to at least one of the plurality of contact holes 462. A regionof the bonding portion 461 that is exposed at the first surface isprovided as a bonding region.

Particularly, since the bonding portion 461 is formed to connect thesecond electrode structure 460 to an external current source (notshown), at least one bonding portion 461 needs to be included in thesecond electrode structure 460.

Since the bonding portion 461 is electrically connected to the externalcurrent source on the surface of the second conductivity typesemiconductor layer 410 to supply current to the contact holes 462, thebonding portion 461 may be electrically separated from the firstelectrode structure 440, the second conductivity type semiconductorlayer 410, and the active layer 420. Electrical separation may beachieved by forming an insulating layer using an insulating materialsuch as a dielectric.

The bonding portion 461 supplies current to the contact holes 462.Further, the bonding portion 461 may be formed so that the bondingportion 461 is not electrically separated from the second conductivitytype semiconductor layer 410 so as to directly spread the current. Thebonding portion 461 may be electrically separated from the secondconductivity type semiconductor layer 410 or not, according to whethercurrent supply to the contact holes 462 or current spreading in thesecond conductivity type semiconductor layer 410 is required.

The cross section of the bonding portion 461 at the active layer 420 maybe smaller than that of the bonding portion 461 at the surface of thesecond conductivity type semiconductor layer 410. In this way, the areaof the active layer 420 is maximized as much as possible in order toensure an increase in luminous efficiency. However, the bonding portion461 at the surface of the second conductivity type semiconductor layer410 needs to have a predetermined area so as to be connected with theexternal current source.

The bonding portion 461 may be located at the center of the lightemitting device 400. In this case, the contact holes 462 are preferablyseparated from the bonding portion 461 by the predetermined distance,and uniformly distributed. Referring to FIG. 18A, the bonding portion461 and the contact holes 462 are uniformly distributed over the secondconductivity type semiconductor layer 410 to optimize the currentspreading. In FIG. 18A, it is assumed that there are one bonding portion461 and eight contact holes 462. However, the number of bonding portion461 and the number of contact holes 462 may be appropriately determinedin consideration of factors for electrical connection state (e.g. theposition of the external current source) and current spreading state(e.g. the thickness of the second conductivity type semiconductor layer410).

When the plurality of contact holes 462 are formed, the bonding portion461 may be directly connected to each of the plurality of contact holes462. In this case, the bonding portion 461 is formed at the center ofthe light emitting device 400, and the contact holes 462 are formedaround the bonding portion 461. Further, the wiring portion 463 maydirectly connect the bonding portion 461 and the contact holes 462 in aradial direction.

Alternatively, some of the plurality of contact holes 462 may bedirectly connected to the bonding portion 461. Other contact holes 462may be connected to the contact holes 462 that are directly connected tothe bonding portion 461, such that these contact holes 462 areindirectly connected to the bonding portion 461. In this way, a largernumber of contact holes 462 can be formed to thereby increase currentspreading efficiency.

In FIGS. 19A through 19C, the wiring portion 463 is formed in the firstelectrode structure 440 and connects the bonding portion 461 and thecontact holes 462 to each other. Therefore, a considerable amount of thefirst electrode structure 440 is located at a rear surface opposite tothe direction in which light is emitted from the active layer 420,thereby increasing luminous efficiency. Particularly, in FIG. 19C, onlythe wiring portion 463 is located in the first electrode structure 440.The second electrode structure 460 is not located at the firstconductivity type semiconductor layer 430, the active layer 420, and thesecond conductivity type semiconductor layer 410. Accordingly, as shownin FIG. 19C, the bonding portion 461 and the contact holes 462 do notaffect light emission, so they have higher luminous efficiency.

The wiring portion 463 is electrically separated from the firstelectrode structure 440. The second electrode structure 460 and thefirst electrode structure 440 include electrodes that have polaritiesopposite to each other to supply external power to the secondconductivity type semiconductor layer 410 and the first conductivitytype semiconductor layer 430, respectively. Therefore, the twoelectrodes must be electrically separated from each other. Electricalseparation may be achieved by forming an insulating layer 480 using aninsulating material, such as a dielectric.

In FIG. 19B, since the bonding portion 461 is located on the surface ofthe second conductivity type semiconductor layer 410, it is possible toobtain the characteristics of a vertical light emitting device. In FIG.19C, since the wiring portion 463 is located in the same plane as thefirst electrode structure 440, it is possible to obtain thecharacteristics of a horizontal light emitting device. Therefore, thelight emitting device 400 has a structure in which the horizontal lightemitting device and the vertical light emitting device are integrated.

Referring to FIGS. 19A through 19C, the first conductivity typesemiconductor layer 430 may be a p-type semiconductor layer, and thefirst electrode structure 440 may be a p-type electrode part. In thiscase, the second conductivity type semiconductor layer 410 may be ann-type semiconductor layer, and the second electrode structure 460 maybe an n-type electrode. The second electrode structure 460 includes thebonding portion 461, the contact holes 462, and the wiring portion 463that are connected to each other. When the second electrode part 460 isformed of the n-type electrode, the second electrode structure 460 maybe electrically separated from the first electrode structure 440 formedof the p-type electrode by the insulating layer 480 that is formed of aninsulating material.

FIG. 20 illustrates the light emission of a light emitting device havingan uneven pattern formed on the surface thereof according to anexemplary embodiment of the present invention. The light emitting deviceaccording to this embodiment includes the second conductivity typesemiconductor layer 410 that forms an outermost surface in a directionwhere emitted light moves. Accordingly, it is easy to form an unevenpattern on the surface by using a well-known method, such asphotolithography. In this case, light emitted from the active layer 420passes through an uneven pattern 490 that is formed on the surface ofthe second conductivity type semiconductor layer 410, and then the lightis extracted. The uneven pattern 490 increases light extractionefficiency.

The uneven pattern 490 may have a photonic crystal structure. Photoniccrystals contain different media with different refractivity in whichthe media are regularly arranged in a crystal-like manner. The photoniccrystals may increase light extraction efficiency by controlling lightin unit of length corresponding to a multiple of a wavelength of light.The photonic crystal structure may be formed according to an appropriateprocess after forming the second conductivity type semiconductor layer410 and the first electrode structure 460. For example, the photoniccrystal structure may be formed by an etching process.

When the uneven pattern 490 is formed on the second conductivity typesemiconductor layer 410, the barrier portion 470 preferably extends tothe inside of the second conductivity type semiconductor layer 410, notthe surface thereof. The barrier portion 470 does not adversely affectthe light extraction efficiency improved by the uneven pattern 490 andseparates a light emitting region into a plurality of light emittingregions.

A semiconductor light emitting device according to another exemplaryembodiment of the present invention will be described with reference toFIGS. 21 through 25.

FIG. 21 is a perspective view illustrating a semiconductor lightemitting device according to another exemplary embodiment of theinvention. FIG. 22 is a plan view illustrating the semiconductor lightemitting device of FIG. 21. Hereinafter, a detailed description will bemade with reference to FIGS. 21 and 22.

A semiconductor light emitting device 500 according to this embodimentincludes a first conductivity type semiconductor layer 511, an activelayer 512, a second conductivity type semiconductor layer 513, a secondelectrode layer 520, a first insulating layer 530, a first electrodelayer 540, and a conductive substrate 550 that are sequentially stacked.Here, the second electrode layer 520 includes a region where a portionof an interface in contact with the second conductivity typesemiconductor layer 513 is exposed. The first electrode layer 540includes at least one contact hole 541. The contact hole 541 iselectrically connected to the first conductivity type semiconductorlayer 511, electrically insulated from the second conductivity typesemiconductor layer 513 and the active layer 512, and extends from onesurface of the first electrode layer 540 to at least part of the firstconductivity type semiconductor layer 511.

In the semiconductor light emitting device 500, the first conductivitytype semiconductor layer 511, the active layer 512, and the secondconductivity type semiconductor layer 513 perform light emission.Hereinafter, they are referred to as a light emitting stack 510. Thatis, the semiconductor light emitting device 500 includes the lightemitting stack 510, the first electrode layer 540, the second electrodelayer 520 and the first insulating layer 530. The first electrode layer540 is electrically connected to the first conductivity typesemiconductor layer 511. The second electrode layer 520 is electricallyconnected to the second conductivity type semiconductor layer 513. Thefirst insulating layer 530 electrically insulates the electrode layers520 and 540 from each other. Further, the conductive substrate 550 isincluded as a substrate to grow or support the semiconductor lightemitting device 500.

Each of the semiconductor layers 511 and 513 may include a semiconductorsuch as a GaN-based semiconductor, a ZnO-based semiconductor, aGaAs-based semiconductor, a GaP-based semiconductor, and a GaAsP-basedsemiconductor. The semiconductor layers may be formed by using, forexample, molecular beam epitaxy (MBE). In addition, each of thesemiconductor layers 511 and 513 may be formed of any one ofsemiconductors, such as a group III-V semiconductor, a group II-VIsemiconductor and Si. Each of the semiconductor layers 511 and 513 isformed by doping the above-described semiconductor with appropriateimpurities in consideration of the conductivity type.

The active layer 512 is a layer where light emission is activated. Theactive layer 320 may be formed of a material having a smaller energyband gap than each of the first and second conductivity typesemiconductor layers 511 and 513. For example, when the first and secondconductivity type semiconductor layers 511 and 513 may be a GaN-basedcompound semiconductor, the active layer 512 may be formed by using anInAlGaN-based compound semiconductor that has a smaller energy bandgapthan GaN. That is, the active layer 512 may includeIn_(x)Al_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1 aresatisfied).

Here, in consideration of characteristics of the active layer 512, theactive layer 512 is preferably not doped with impurities. A wavelengthof emitted light may be controlled by adjusting a mole ratio ofconstituents. Therefore, the semiconductor light emitting device 500 mayemit any one of infrared light, visible light, and UV light according tothe characteristics of the active layer 512.

Each of the electrode layers 520 and 540 is formed in order to applyvoltage to the same conductivity type semiconductor layer. Therefore, inconsideration of electroconductivity, the electrode layers 520 and 540may be formed of metal. That is, the electrode layers 520 and 540include electrodes that electrically connect the semiconductor layers511 and 513 to an external current source (not shown). The electrodelayers 520 and 540 may include, for example, Ti as an n-type electrode,and Pd or Au as a p-type electrode.

The first electrode layer 540 is connected to the first conductivitytype semiconductor layer 511, and the second electrode layer 520 isconnected to the second conductivity type semiconductor layer 513. Thatis, since the first and second electrode layers 540 and 520 areconnected to the different conductivity type semiconductor layers fromeach other, the first and second layers 540 and 520 are electricallyseparated from each other by the first insulating layer 530. The firstinsulating layer 530 may be formed of a material having lowelectroconductivity. The first insulating layer 530 may include, forexample, an oxide such as SiO₂.

The second electrode layer 520 may reflect light generated from theactive layer 512. Since the second electrode layer 520 is located belowthe active layer 512, the second electrode layer 520 is located at asurface opposite to a direction, in which the semiconductor lightemitting device 500 emits light, on the basis of the active layer 512.Light moving from the active layer 512 to the second electrode layer 520is opposite to the light emitting direction of the semiconductor lightemitting device 500, and thus the light moving toward the secondelectrode layer 520 needs to be reflected to increase luminousefficiency. Therefore, when the second electrode layer 520 has lightreflectivity, the reflected light moves toward a light emitting surfaceto thereby increase the luminous efficiency of the semiconductor lightemitting device 500.

In order to reflect the light generated from the active layer 512, thesecond electrode layer 520 may be formed of metal that appears white ina visible light region. For example, the white metal may be any one ofAg, Al, and Pt.

The second electrode layer 520 includes a region where a portion of theinterface in contact with the second conductivity type semiconductorlayer 513 is exposed. A lower surface of the first electrode layer 540is in contact with the conductive substrate 550, and the first electrodelayer 540 is electrically connected to an external current source (notshown) through the conductive substrate 550. However, the secondelectrode layer 520 requires a separate connecting region so as to beconnected to the external current source. Therefore, the secondelectrode layer 520 includes an area that is exposed by partiallyetching the light emitting stack 510.

In FIG. 21, an example of a via hole 514 is shown. The via hole 514 isformed by etching the center of the light emitting stack 510 to form anexposed region of the second electrode layer 520. An electrode padportion 560 may be further formed at the exposed region of the secondelectrode layer 520. The second electrode layer 520 may be electricallyconnected to the external power source by the exposed region thereof. Atthis time, the second electrode layer 520 is electrically connected tothe external power source by using the electrode pad portion 560. Thesecond electrode layer 520 may be electrically connected to the externalcurrent source by a wire or the like. For convenient connection to theexternal current source, the diameter of the via hole preferablyincreases from the second electrode layer toward the first conductivitytype semiconductor layer.

The via hole 514 is formed by selective etching. In general, the lightemitting stack 510 including the semiconductors is only etched, and thesecond electrode layer 520 including the metal is not etched. Thediameter of the via hole 514 may be appropriately determined by thoseskilled in the art in consideration of the light emitting area,electrical connection efficiency, and current spreading in the secondelectrode layer 520.

The first electrode layer 540 includes at least one contact hole 541.The contact hole 541 is electrically connected to the first conductivitytype semiconductor layer 511, electrically insulated from the secondconductivity type semiconductor layer 513 and the active layer 512, andextends to at least part of the first conductivity type semiconductorlayer 511. The first electrode layer 540 includes at least one contacthole 541 in order to connect the first conductivity type semiconductorlayer 511 to the external current source. The contact hole 541penetrates the second electrode layer 520 between the first electrodelayer 540 and the second conductivity type semiconductor layer 513, thesecond conductivity type semiconductor layer 513, and the active layer512, and extends to the first conductivity type semiconductor layer 511.Further, the contact hole 541 is formed of an electrode material.

When the contact hole 541 is only used for the electrical connection,the first electrode layer 540 may include one contact hole 541. However,in order to uniformly spread current that is transmitted to the firstconductivity type semiconductor layer 511, the first electrode layer 540may include a plurality of contact holes 541 at predetermined positions.

The conductive substrate 550 is formed in contact with and iselectrically connected to the first electrode layer 540. The conductivesubstrate 550 may be a metallic substrate or a semiconductor substrate.When the conductive substrate 550 is the metallic substrate, theconductive substrate 550 may be formed of any one of Au, Ni, Cu, and W.Further, when the conductive substrate 550 is the semiconductorsubstrate, the conductive substrate 550 may be formed of any one of Si,Ge, and GaAs. The conductive substrate 550 may be a growth substrate.Alternatively, the conductive substrate 550 may be a support substrate.After a non-conductive substrate, such as a sapphire substrate, havingrelatively small lattice-mismatching is used as a growth substrate, thenon-conductive substrate is removed, and the support substrate isbonded.

Also, when the conductive substrate 550 is the support substrate, theconductive substrate 550 may be formed by a plating method or asubstrate bonding method. As a method of forming the conductivesubstrate 550 in the semiconductor light emitting device 500, theplating method of forming a plating seed layer to form a substrate orthe substrate bonding method of separately preparing the conductivesubstrate 550 and bonding the conductive substrate 550 by using aconductive adhesive, such as Au, Au—Sn, and Pb—Sr may be used.

FIG. 22 is a plan view illustrating the semiconductor light emittingdevice 500. The via hole 514 is formed in the top surface of thesemiconductor light emitting device 500, and the electrode pad portion560 is located at the exposed region of the second electrode layer 520.In addition, though not shown in the top surface of the semiconductorlight emitting device 500, the contact holes 541 are shown as a dottedline in order to display the positions of the contact holes 541. Thefirst insulating layer 530 may extend and surround the contact hole 541so that the contact hole 541 is electrically separated from the secondelectrode layer 520, the second conductivity type semiconductor layer513, and the active layer 512. This will be described in more detailwith reference to FIGS. 23B and 23C.

FIGS. 23A through 23C are cross-sectional views of the semiconductorlight emitting device shown in FIG. 22 taken along the lines A-A′, B-B′,and C-C′. The line A-A′ is taken to show a cross section of thesemiconductor light emitting device 500. The line B-B′ is taken to showa cross section that includes the contact holes 541 and the via hole514. The line C-C′ is taken to show a cross section that only includesthe contact holes 541. Hereinafter, the description will be made withreference to FIGS. 21 through 23C.

Referring to FIG. 23A, neither the contact hole 541 nor the via hole 514is shown. Since the contact hole 541 is not connected by using aseparate connecting line but is electrically connected by the firstelectrode layer 540, the contact hole 541 is not shown in the crosssection in FIG. 23.

Referring to FIGS. 23B and 23C, the contact hole 541 extends from theinterface between the first electrode layer 540 and the second electrodelayer 520 to the inside of the first conductivity type semiconductorlayer 511. The contact hole 541 passes through the second conductivitytype semiconductor layer 513 and the active layer 512 and extends to thefirst conductivity type semiconductor layer 511. The contact hole 541extends at least to the interface between the active layer 512 and thefirst conductivity type semiconductor layer 511. Preferably, the contacthole 541 may extend to part of the first conductivity type semiconductorlayer 511. However, the contact hole 541 is used for the electricalconnection and current spreading. Once the contact hole 541 is incontact with the first conductivity type semiconductor layer 511, thecontact hole 541 does not need to extend to the outer surface of thefirst conductivity type semiconductor layer 511.

The contact hole 541 needs to have a predetermined area in order tospread current in the first conductivity type semiconductor layer 511. Apredetermined number of contact holes 541 may be provided, and may eachhave an area small enough to allow for uniform current spreading in thefirst conductivity type semiconductor layer 511. The number of contactholes may be appropriately selected in due consideration of the factthat a small number of contact holes 541 deteriorate electricalcharacteristics due to non-uniform current spreading, while a largenumber of contact holes 541 cause difficulties in the formation processthereof and cause a reduction in a light emitting area due to a decreasein the area of the active layer. Each of the contact holes 541 isrealized so as to have as small an area as possible yet retain a shapeeffective for current spreading. The contact hole 541 extends from thesecond electrode layer 520 into the first conductivity typesemiconductor layer 511. Since the contact hole 541 is used for thecurrent spreading in the first conductivity type semiconductor layer,the contact hole 541 needs to be electrically separated from the secondconductivity type semiconductor layer 513 and the active layer 512.Therefore, the contact hole 541 may be electrically separated from thesecond electrode layer 520, the second conductivity type semiconductorlayer 513 and the active layer 512. Accordingly, the first insulatinglayer 530 may extend to surround the circumference of the contact hole530. This electrical separation may be performed by using an insulatingmaterial such as a dielectric.

In FIG. 23B, the exposed region of the second electrode layer 520 servesas an electrical connection point for an external power source (notshown) of the second electrode layer 520. The electrode pad portion 560may be placed on the exposed region. Here, the second insulating layer570 is formed on the inner side surface of the via hole 514 to therebyelectrically separate the multilayer laminate structure 510 and theelectrode pad portion 560.

Referring to FIG. 23A, the first electrode layer 540 and the secondelectrode layer 520 are formed on the same layer, so that thesemiconductor light emitting device 500 has the characteristics of ahorizontal semiconductor light emitting device. Referring to FIG. 23B,the electrode pad portion 560 is placed on the surface of the secondelectrode layer 520, so that the semiconductor light emitting device 500may have the characteristics of a vertical light emitting device.Consequently, the semiconductor light emitting device 500 has acombination structure having the characteristics of both vertical andhorizontal semiconductor light emitting devices.

In FIGS. 23A and 23C, the first conductivity type semiconductor layer511 is an n-type semiconductor layer, and the first electrode layer 540may be an n-type electrode. In this case, the second conductivity typesemiconductor layer 513 may be a p-type semiconductor layer, and thesecond electrode layer 520 may be a p-type electrode. Thus, the firstelectrode layer 540, the n-type electrode, and the second electrodelayer 520, the p-type electrode, may be electrically insulated from eachother by the first insulating layer 530 provided therebetween.

FIG. 24 illustrates light emission in a semiconductor light emittingdevice having an uneven pattern on the surface thereof, according tothis embodiment. A description of the previously described elements willbe omitted.

The outermost layer of the semiconductor light emitting device 500, in adirection in which emitted light moves, is the first conductivity typesemiconductor layer 511. Thus, the uneven pattern 580 may be easilyformed on the surface by using a method known in the art such as aphotolithography method. In this case, light emitted from the activelayer 512 is extracted through the uneven pattern 580 formed on thesurface of the first conductivity type semiconductor layer 511, therebyenhancing light extraction efficiency.

The uneven pattern may be a photonic crystal structure. Photoniccrystals refer to media having different refractive indices that areregularly arranged like crystals. The photonic crystals can increaselight extraction efficiency by controlling light in the unit of lengthcorresponding to a multiple of a wavelength of light.

FIG. 25 illustrates a second electrode layer exposed on a corner portionin the semiconductor light emitting device according to this embodiment.

According to another aspect of the present invention, a method ofmanufacturing a semiconductor light emitting device includes:sequentially stacking a first conductivity type semiconductor layer511′, an active layer 512′, a second conductivity type semiconductorlayer 513′, a second electrode layer 520′, an insulating layer 530′, afirst electrode layer 540′, and a conductive substrate 550′; forming anexposed region in a part of the interface of the second electrode layer520′ with the second conductivity type semiconductor layer 513′; andforming at least one contact hole 541′ extending from one surface of thefirst electrode layer 540′ to at least a part of the first conductivitytype semiconductor layer 511′ and electrically insulated from the secondconductivity type semiconductor layer 513′ and the active layer 512′,such that the first electrode layer 540′ is electrically connected withthe first conductivity type semiconductor layer 511′.

The exposed region of the second electrode layer 520′ may be provided byforming the via hole 510′ in the light emitting stack 510′ (see FIG.21), or by mesa-etching the light emitting stack 510′ (see FIG. 25). Inthis embodiment, a description of the same elements as those of theembodiment depicted in FIG. 21 will be omitted in the interest ofclarity.

Referring to FIG. 25, one corner of the semiconductor light emittingdevice 500′ is mesa-etched. The etching is performed on the lightemitting stack 510′ so as to expose the second electrode layer 520′ atthe interface with the second conductivity type semiconductor layer513′. The exposed region of the second electrode layer 520′ is formed atthe corner of the semiconductor light emitting device 500′. The processof forming the exposed region at the corner is a simpler process thanthe process of forming the via hole, and may facilitate a subsequentelectrical connection process.

Referring to FIGS. 26 through 36, a semiconductor light emitting deviceaccording to another exemplary embodiment of the present invention willnow be described.

FIG. 26 is a schematic perspective view illustrating a semiconductorlight emitting device according to this embodiment. FIG. 27 is a topplan view illustrating the semiconductor light emitting device depictedin FIG. 26, and FIG. 28 is a cross-sectional view taken along line A-A′,illustrating the semiconductor light emitting device depicted in FIG.27. Hereinafter, a description will be made with reference to FIGS. 26through 28.

A semiconductor light emitting device 600, according to this embodiment,includes a first conductivity type semiconductor layer 611, an activelayer 612, a second conductivity type semiconductor layer 613, a secondelectrode layer 620, an insulating layer 630, a first electrode layer640 and a conductive substrate 650 that are sequentially stacked. Here,in order to be electrically connected with the first conductivity typesemiconductor layer 611, the first electrode layer 640 includes at leastone contact hole 641. Here, the at least one contact hole 641 extendsfrom one surface of the first electrode layer 640 up to at least a partof the first conductivity type semiconductor layer 611, and iselectrically insulated from the second conductivity type semiconductorlayer 613 and the active layer 612. The first electrode layer 640 is notan essential element in this embodiment. Although not shown, the firstelectrode layer may not be included, and the contact hole 641 may beformed from one surface of the conductive substrate. That is, to beelectrically connected with the first conductivity type semiconductorlayer 111, the conductive substrate 650 may include at least one contacthole 641 extending from one surface of the conductive substrate 650 upto at least a part of the first conductivity type semiconductor layer611 and electrically insulated from the second conductivity typesemiconductor layer 113 and the active layer 112. Here, the conductivesubstrate is electrically connected to an external power source (notshown), and the first conductivity type semiconductor layer receivesvoltage through the conductive substrate.

The second electrode layer 620 has an exposed region 614 that is formedon a part of its interface with the second conductivity typesemiconductor layer 613 by etching the first conductivity typesemiconductor layer 611, the active layer 612 and the secondconductivity type semiconductor layer 613. An etch stop layer 621 isformed on the exposed region 614.

The light emission of the semiconductor light emitting device 600 iscarried out by the first conductivity type semiconductor layer 611, theactive layer 612, and the second conductivity type semiconductor layer613, and thus they are referred to as a light emitting stack 610. Thatis, the semiconductor light emitting device 600 includes the lightemitting stack 610, the first electrode layer 640 electrically connectedwith the first conductivity type semiconductor layer 611 by the contacthole 641, the second electrode layer 620 electrically connected with thesecond conductivity type semiconductor layer 613, and the insulatinglayer 630 electrically insulating the electrode layers 620 and 640. Inaddition, the conductive substrate 650 is provided to support thesemiconductor light emitting device 600.

The first conductivity type semiconductor layer 611 and the secondconductivity type semiconductor layer 613 may include, for example, asemiconductor material such as a GaN-based semiconductor, a ZnO-basedsemiconductor, a GaAs-based semiconductor, a GaP-based semiconductor, ora GaAsP-based semiconductor; however, the semiconductor layers 611 and613 are not limited thereto. The semiconductor layers 611 and 613 mayalso be formed of a material appropriately selected from the groupconsisting of group III-V semiconductors, group II-VI semiconductors,and Si. In addition, the semiconductor layers 611 and 613 may be dopedwith n-type impurities or p-type impurities in consideration of theconductivity type of each of the semiconductors described above.

The active layer 612 activates light emission, and is formed of amaterial having a smaller energy band gap than the energy band gaps ofthe first conductivity type semiconductor layer 611 and the secondconductivity type semiconductor layer 613. For example, when the firstconductivity type semiconductor layer 611 and the second conductivitytype semiconductor layer 613 are GaN-based compound semiconductors, theactive layer 612 may be formed by using an InAlGaN-based compoundsemiconductor having a smaller energy band gap than that of GaN. Thatis, the active layer 612 may include In_(x)Al_(y)Ga_((1-x-y))N (0≦x≦1,0≦y≦1, 0≦x+y≦1).

Here, the active layer 612 may not be doped with impurities due to thecharacteristics of the active layer 612, and the wavelength of emittedlight can be regulated by controlling the mole ratio of materials.Accordingly, the semiconductor light emitting device 600 can emitinfrared light, visible light or ultraviolet light depending on thecharacteristic of the active layer 612.

The first electrode layer 640 and the second electrode layer 620 serveto supply voltage to the semiconductor layers of the same conductivitytype, respectively. The semiconductor layers 611 and 613 areelectrically connected with an external power source (not shown) by theelectrode layers 620 and 640.

The first electrode layer 640 is connected with the first conductivitytype semiconductor layer 611, and the second electrode layer 620 isconnected with the second conductivity type semiconductor layer 613.Thus, the first electrode layer 640 and the second electrode layer 620are electrically separated from each other by the first insulating layer630. The first insulating layer 630 may be formed of a material having alow level of electric conductivity, for example, an oxide such as SiO₂.

To be electrically connected with the first conductivity typesemiconductor layer 611, the first electrode layer 640 includes at leastone contact hole 641 extending up to a part of the first conductivitytype semiconductor layer 611 and electrically insulated from the secondconductivity type semiconductor layer 613 and the active layer 612.Here, this electrical insulation may be made by the extension of theinsulating layer 630 placed between the first and second electrodelayers. The contact hole 641 extends to the first conductivity typesemiconductor layer 611 through the second electrode layer 620, theinsulating layer 630 and the active layer 612, and has an electrodematerial therein. The first electrode layer 640 is electricallyconnected with the first conductivity type semiconductor layer 611 bythe contact hole 641, thereby connecting the first conductivity typesemiconductor layer 611 to an external power source (not shown).

In the event that the contact hole 641 is formed only for an electricalconnection with the first conductivity type semiconductor layer 611, thefirst electrode layer 640 may have a single contact hole 641. However,the first electrode layer 640 may include one or more contact holes 641at predetermined locations in order to ensure uniform current spreadingin the first conductivity type semiconductor layer 611.

The second electrode layer 620 is placed under the active layer 612, onthe opposite side to a direction that light is emitted from thesemiconductor light emitting device 600 with reference to the activelayer 612. Accordingly, light moving toward the second electrode layer620 is reflected, and this enhances luminous efficiency.

The second electrode layer 620 may be formed of a white metal in avisible light region in order to reflect light generated from the activelayer 612. For example, the second electrode layer 620 may include atleast one of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt and Au.

The second electrode layer 620 has an exposed portion at its interfacewith the second conductivity type semiconductor layer 613. This exposedportion is formed by etching the first conductivity type semiconductorlayer 611, the active layer 612 and the second conductivity typesemiconductor layer 613. The etch stop layer 621 is formed on theexposed region 614. The first electrode layer 640, in contact with theconductive substrate 650 placed thereunder, can be connected with anexternal power source, whereas the second electrode layer 620 requires aseparate connection region for a connection with the external powersource (not shown). Therefore, the second electrode layer 620 has theexposed region 614 on a part of its interface with the secondconductivity type semiconductor layer 613 by etching a portion of thelight emitting stack 610. In this manner, the second conductivity typesemiconductor layer 613 is connected to the external power source (notshown) by the second electrode layer 620.

The area of the exposed region 614 may be appropriately selected bythose skilled in the art in consideration of a light emitting area,electrical connection efficiency and current spreading in the secondelectrode layer 620. FIGS. 27 through 29 illustrate an embodiment inwhich the exposed region 614 of the second electrode layer 620 is formedat the corner by etching the corner of the light emitting stack 610.

The exposed region 614 is formed by selective etching by which only apart of the light emitting stack 610 is etched while the secondelectrode layer 620, typically containing metal, is not etched. However,full control over this selective etching that etches only the part ofthe light emitting stack 610 is hard to implement. For this reason, thesecond electrode layer, placed under the light emitting stack 610, mayalso be etched in part. The second electrode layer 620, etched in part,may cause the metallic material of the second electrode layer 620 tobond with the second conductivity type semiconductor layer 613,resulting in current leakage. Therefore, the etch stop layer 621 isformed on a region where the etching of the light emitting stack 610 iscarried out (i.e., the exposed region of the second electrode layer620).

The etch-stop layer 621 can prevent the metal, forming the secondelectrode layer 620, from being bonded to the side of the light-emittingstack 610, thereby reducing a leakage current and facilitating etching.The etch-stop layer 621 may be formed of materials used to prevent theetching of the light-emitting stack 600. Examples of these materials mayinclude insulating materials such as a silicon oxide or a nitride oxide,SiO₂, SiO_(x)N_(y), or Si_(x)N_(y), for example. However, the presentinvention is not limited thereto. Here, the etch-stop layer 621 is notnecessarily formed of insulating materials, and may be formed ofconductive materials, which do not have any adverse effect on theoperation of the device. Therefore, as long as the etch-stop layer 621provides etch-stop performance, the etch-stop layer 621 may beappropriately formed of conductive materials.

Furthermore, an electrode pad portion 660 may pass through the etch-stoplayer 621 and be formed in the exposed region 614. The electrode padportion 660 passes through the etch-stop layer 621 and is electricallyconnected to the second electrode layer. Here, an electrical connectionbetween the second electrode layer 620 and an external power source (notshown) is further facilitated.

The conductive substrate 650 is located under the first electrode layer640. Further, the conductive substrate 650 comes into contact with thefirst electrode layer 640 and is electrically connected thereto. Theconductive substrate 650 may be a metallic substrate or a semiconductorsubstrate. The conductive substrate 650 may be formed of a materialincluding any one of Au, Ni, Al, Cu, W, Si, Se, and GaAs, for example,Si—Al alloys. Here, the conductive substrate 650 may be formed byplating or bonding according to the selected material. The conductivesubstrate 650 may be a support substrate that is bonded after a sapphiresubstrate with a relatively small mismatch is used as a growthsubstrate, and is then removed.

FIG. 27 is an upper plan view illustrating the semiconductor lightemitting device 600. Though not shown in the upper surface of thesemiconductor light emitting device 600, the contact holes 641 areindicated by dotted lines in order to identify where the contact holes641 are located. An insulating layer 630 may be extended around thecontact holes 641 so that the contact holes 641 are electricallyinsulated from the second electrode layer 620, the second conductivitytype semiconductor layer 613, and the active layer 612. This will bedescribed in detail with reference to FIG. 28.

FIG. 28 is a cross-sectional view taken along the line A-A′ of thesemiconductor light emitting device, shown in FIG. 27. The line A-A′ isselected to take in a cross-section including the contact holes 641 andthe exposed region 614.

Referring to FIG. 28, the contact holes 641 pass through the interfaceof the first electrode layer 640, the second electrode layer 620, thesecond conductivity type semiconductor layer 613, and the active layer612, and are extended to the inside of the first conductivity typesemiconductor layer 611. The contact holes 641 are extended to at leastthe active layer 612 and the interface of the first conductivity typesemiconductor layer 611, preferably, to a portion of the firstconductivity type semiconductor layer 611. Here, the contact holes 641are formed to provide an electrical connection and current spreading forthe first conductivity type semiconductor layer 611, which are achievedwhen the contact holes 641 come into contact with the first conductivitytype semiconductor layer 611. The contact holes 641 do not have to beextended to the outer surface of the first conductivity typesemiconductor layer 611.

The contact holes 641 are formed to achieve current spreading of thefirst conductivity type semiconductor layer 611 and may have apredetermined area. As for the contact holes 641, a predetermined numberof contact holes, which are as small as possible in order to provideuniform current spreading in the first conductivity type semiconductorlayer 611, may be formed. When an insufficient number of contact holes641 are formed, it becomes difficult to achieve current spreading,thereby worsening electrical characteristics. On the other hand, when anexcessive number of contact holes 641 are formed, processingdifficulties in forming the contact holes 641 and a reduction in alight-emitting area due to a reduction in the area of the active layerare caused. Therefore, the number of contact holes 641 may beappropriately selected. Therefore, the contact holes 641 are formed insuch a manner that the contact holes 641 have as small an area aspossible yet provide effective current spreading.

The contact holes 641 are extended from the first electrode layer 640 tothe inside of the first conductivity type semiconductor layer 611. Sincethe contact holes 641 are formed for the current spreading of the firstconductivity type semiconductor layer, the contact holes 641 need to beelectrically insulated from the second conductivity type semiconductorlayer 613 and the active layer 612. Therefore, the insulating layer 630may be extended to surround the contact holes 641.

In FIG. 28, the second electrode layer 620 includes the exposed region614, which is an exposed portion of the interface between the secondconductivity type semiconductor layer 613 and the second electrode layer620. The exposed region 614 is formed to provide an electricalconnection between the second electrode layer 620 and an external powersource (not shown). The etch-stop layer 621 is formed in the exposedregion 614. The exposed region 614 may include the electrode pad portion660 that passes through the etch-stop layer 621 and is electricallyconnected to the second electrode layer 620. Here, the insulating layer670 may be formed on the inside surface of the exposed region 614 inorder to electrically separate the light-emitting stack 610 from theelectrode pad portion 660.

In FIG. 28, since the first electrode layer 641 and the second electrodelayer 620 are located in the same plane, the semiconductor lightemitting device 600 has the characteristics of a horizontal typesemiconductor light emitting device. Since the electrode pad portion 660is located on the surface of the first conductivity type semiconductorlayer 611, the semiconductor light emitting device 600 may also have thecharacteristics of a vertical semiconductor light emitting device.Therefore, the semiconductor light emitting device 600 has aconfiguration in which the characteristics of both vertical andhorizontal type semiconductor light emitting devices are combined.

FIGS. 29 through 31 are views illustrating a semiconductor lightemitting device according to another exemplary embodiment of theinvention. FIG. 29 is a perspective view illustrating the semiconductorlight emitting device. FIG. 30 is an upper plan view of thesemiconductor light emitting device of FIG. 20. FIG. 31 is across-sectional view taken along the line A-A′ of the semiconductorlight emitting device of FIG. 30.

As shown in FIGS. 29 through 31, a central portion of a light-emittingstack 710 is etched, and an exposed region 714, which is a portion ofthe interface between a second electrode layer 720 and a secondconductivity type semiconductor layer. A description of componentsidentical to those described above will be omitted in the interest ofclarity. Here, an etch-stop layer 721 may be partially removed and maybe electrically connected to an external power source (not shown). Anelectrode pad portion 760 that passes through the etch-stop layer 721and is electrically connected to the second electrode layer 720 may beincluded. The etch-stop layer 721 may be connected to the external powersource (not shown) using wires. For convenience of explanation, theexposed region 714 increases from a first conductivity typesemiconductor layer toward a second electrode layer.

FIGS. 32 and 33 are views illustrating a modified embodiment of asemiconductor light emitting device according to an exemplary embodimentof the invention. FIG. 32 is a perspective view illustrating asemiconductor light emitting device. FIG. 33 is a side sectional viewillustrating a semiconductor light emitting device. Here, an upper planview of the semiconductor light emitting device is similar to that ofFIG. 27. Similar to FIG. 28, FIG. 33 is a cross-sectional view takenalong the line A-A′. A description of the same components, having beendescribed above, will be omitted.

Referring to FIGS. 32 and 33, a light-emitting stack 610′ is etched tothereby expose a second electrode layer. An etch-stop layer 621′, whichis formed on the exposed region, is extended to the sides of a secondconductivity type semiconductor layer 613′ and an active layer 612′. Inthis way, as described above, while the first conductivity typesemiconductor layer 611′ is being etched, metallic materials of thesecond electrode layer can be prevented from being bonded to thesemiconductor side, and the active layer 612′ can also be protected.

Here, a method of manufacturing the above-described semiconductor lightemitting device will be omitted.

FIGS. 34A through 34D are cross-sectional views illustrating a method ofmanufacturing a semiconductor light emitting device according to anexemplary embodiment of the invention. More specifically, a method ofmanufacturing the semiconductor light emitting device, shown in FIGS. 26through 28, will be described.

First, as shown in FIG. 34A, the first conductivity type semiconductorlayer 611, the active layer 612, the second conductivity typesemiconductor layer 613, and the second electrode layer 620 are stackedon a non-conductive substrate 680 in a sequential manner.

Here, the semiconductor layer and the active layer may be stacked usinga known process, such as Metal Organic Chemical Vapor Deposition(MOCVD), Molecular Beam Epitaxy (MBE), or Hydride Vapor Phase Epitaxy(HVPE). As for the non-conductive substrate 680, a sapphire substratethat facilitates the growth of semiconductor layers may be used.

The second electrode layer 620 is stacked while the etch-stop layer 621is formed in a region to be exposed by etching the first conductivitytype semiconductor layer 611, the active layer 612, and the secondconductivity type semiconductor layer 613.

The insulating layer 630 and the conductive substrate 650 are thenformed on the second electrode layer 620. Here, as shown in FIG. 34B,the first electrode layer 640 may be formed between the insulating layer630 and the conductive substrate 650.

In order that the conductive substrate 650 is electrically connected tothe first conductivity type semiconductor layer 611, the conductivesubstrate 650 includes the one or more contact holes 641 that areelectrically insulated from the second conductivity type semiconductorlayer 613 and the active layer 612 and are extended to a portion of thefirst conductivity type semiconductor layer 611 from one surface of theconductive substrate 650.

As shown in FIG. 34A, when the first electrode layer 640 is formedbetween the insulating layer 630 and the conductive substrate 650, thecontact holes 641 are formed starting from one surface of the firstelectrode layer 640. That is, in order that the first electrode layer640 is electrically connected to the first conductivity typesemiconductor layer 611, the first electrode layer 640 includes one ormore contact holes 641 that are electrically insulated from the secondconductivity type semiconductor layer 613 and the active layer 612 andare extended from the one surface of the first electrode layer 640 to aportion of the first conductivity type semiconductor layer 611.

Here, as the contact holes 641 are formed for the current spreading ofthe first conductivity type semiconductor layer 611, the contact holes641 need to be electrically insulated from the second conductivity typesemiconductor layer 613 and the active layer 612. Therefore, theinsulating layer 630 may be extended to surround the contact holes 641.

As shown in FIG. 34C, which is a reversed view of FIG. 34B, thenon-conductive substrate 680 is removed, a portion of each of the firstconductivity type semiconductor layer 611, the active layer 612, and thesecond conductivity type semiconductor layer 613 is etched to therebyform the exposed region 614 in a portion of the interface between thesecond electrode layer 620 and the second conductivity typesemiconductor layer 613.

The exposed region 614 is formed using selective etching so that thelight-emitting stack 610 is partially etched while the second electrodelayer 620, which generally contains a metal, is not selected.

As described above, since it is difficult to completely controlselective etching to etch a region of the light-emitting stack 610, thesecond electrode layer 620, located under the light-emitting stack 610,may be partially etched. In this embodiment, the etch-stop layer 621 isformed in a region subjected to etching to thereby facilitate etching,so that the metal of the second electrode layer 620 is prevented frombeing bonded to the side of the light-emitting stack 610, therebyreducing a leakage current.

As shown in FIG. 34D, one region of the etch-stop layer 621 may beremoved in order to provide an electrical connection between the secondelectrode layer 620 and the external power source. Here, the electrodepad portion 660 may be formed in a region where the etch-stop layer 621is removed. Furthermore, in order to electrically insulate thelight-emitting stack 610 and the electrode pad portion 660, theinsulating layer 670 may be formed on the inside surface of thelight-emitting stack, where etching has been performed.

FIGS. 34A through 34D are views illustrating an example in which oneedge of the light-emitting stack 610 is etched, and the exposed region614 of the second electrode layer 620 is formed in the etched edge. Whenthe central portion of the light-emitting stack 610 is etched, thesemiconductor light emitting device, as shown in FIG. 29, may bemanufactured.

FIGS. 35A through 35D are cross-sectional views illustrating a method ofmanufacturing a modified embodiment of a semiconductor light emittingdevice according to an exemplary embodiment of the invention. Morespecifically, a method of manufacturing the semiconductor light emittingdevice, shown in FIGS. 32 and 33, will be described. A description ofthe same components, having described above with reference to FIGS. 34Athrough 34D, will be omitted.

First, as shown in FIG. 35A, the first conductivity type semiconductorlayer 611′, the active layer 612′, the second conductivity typesemiconductor layer 613′, and a second electrode layer 620′ are stackedon a non-conductive substrate 680′ in a sequential manner.

The second electrode layer 620′ is stacked while the etch-stop layer621′ is formed in a region to be exposed by etching the firstconductivity type semiconductor layer 611′, the active layer 612′, andthe second conductivity type semiconductor layer 613′. Here, beforeetching a light-emitting stack 610′ in order to form an exposed region614′, as shown in FIG. 36A, portions of the second conductivity typesemiconductor layer 613′, the active layer 612′, and the secondconductivity type semiconductor layer 613′ are primarily etched. Theetch-stop layer 621′ is extended along the portions exposed by primarilyetching the second conductivity type semiconductor layer 613′, theactive layer 612′, and the first conductivity type semiconductor layer611′.

Here, as shown in FIG. 35C, when etching the light-emitting stack 610′in order to form the exposed region 614′ in the second electrode layer620′, it is possible to etch only the first conductivity typesemiconductor layer 611′. Therefore, the active layer can also beprotected.

As shown in FIG. 35B, an insulating layer 630′, a first electrode layer640′, and a conductive substrate 650′ are formed on the second electrodelayer 620′.

Here, in order that the first electrode layer 640′ is electricallyconnected to the first conductivity type semiconductor layer 611′, thefirst electrode layer 640′ includes one or more contact holes 641 thatare electrically insulated from the second conductivity typesemiconductor layer 613′ and the active layer 612′ and are extended fromone surface of the first electrode layer 640′ to a portion of the firstconductivity type semiconductor layer 611′. Here, since the contactholes 641′ are formed for the current spreading of the firstconductivity type semiconductor layer 611′, the contact holes 641′ needto be electrically insulated from the second conductivity typesemiconductor layer 613′ and the active layer 612′. Therefore, theinsulating layer 630′ may be extended to surround the contact holes641′.

As shown in FIG. 35C, which is a reversed view of FIG. 35B, the exposedregion 614′ is formed in the second electrode layer 620′ to partiallyexpose the interface between the second conductivity type semiconductorlayer and the second electrode layer. First, the non-conductivesubstrate 680′ is removed, and the first conductivity type semiconductorlayer 611′ is etched. As described above, in FIG. 36A, since the activelayer 612′ and the second conductivity type semiconductor layer 613′have undergone etching, the exposed region 614′ can only be formed byetching the first conductivity type semiconductor layer.

As described above, when the light-emitting stack 610′ is etched, theetch-stop layer 621′ may be formed in the exposed region 614′ of thesecond electrode layer 620′, thereby facilitating etching. Furthermore,the first conductivity type semiconductor layer 611′ is only etched dueto the primary etching, performed as shown in FIG. 35A, therebyprotecting the active layer.

As shown in FIG. 35D, in order to connect the second electrode layer620′ to an external power source, one region of the etch-stop layer621′, which is formed on the exposed region 614′, may be removed. Here,an electrode pad portion 660′ may be formed on the removed portion ofthe etch-stop layer 621′ so as to be electrically connected to thesecond electrode layer. Here, unlike the process shown in FIGS. 34Athrough 34D, only the first conductivity type semiconductor layer 611′is exposed. Therefore, an insulating layer, which is formed toelectrically insulate the electrode pad portion 660′ from the secondelectrode layer 610′, is not required.

When mounting the semiconductor light emitting devices 600, 600′, and700, according to the exemplary embodiments of the invention, theconductive substrates 650, 650′, and 750 are each electrically connectedto the first lead frame, while the electrode pad portions 660, 660′, and760 are each electrically connected to the second lead frame usingwires. That is, the mounting process may be performed using die-bondingmixed with wire bonding. That is, since the semiconductor light emittingdevices 600, 600′, and 700 may be mounted using die-bonding mixed withwire bonding, maximum luminance efficiency can be ensured, and themanufacturing process can be performed at relatively low cost.

FIG. 36 is a schematic cross-sectional view illustrating anothermodified embodiment of a semiconductor light emitting device accordingto an exemplary embodiment of the invention. Referring to FIG. 36, likethe above-described embodiments, a semiconductor light emitting device600″ according to this modified embodiment includes a first conductivitytype semiconductor layer 611″, an active layer 612″, a secondconductivity type semiconductor layer 613″, a second electrode layer620″, an insulating layer 630″, a first electrode layer 640″, aconductive substrate 650″, which are stacked in a sequential manner, anetch-stop layer 621″, and an electrode pad portion 660″. In order thatthe first electrode layer 640″ is electrically connected to the firstconductivity type semiconductor layer 611″, the first electrode layer640″ includes one or more contact holes 641″ that are electricallyinsulated from the second conductivity type semiconductor layer 613″ andthe active layer 612″ and are extended to a portion of the firstconductivity type semiconductor layer 611″ from one surface of the firstelectrode layer 640″. In this modified embodiment, a passivation layer670″ having an uneven structure is added. Since components, which aredescribed in the same terms, have been described in the above-describedembodiment, only the passivation layer 670″ will be described.

When a configuration having the first conductivity type semiconductorlayer 611″, the active layer 612″, and the second conductivity typesemiconductor layer 613″ are defined as a light-emitting structure, thepassivation layer 670″ is formed to cover the sides of thelight-emitting structure, thereby protecting the active layer 612″ inparticular. Here, as shown in FIG. 36, the passivation layer 670″ may beformed on the top surface as well as the side surfaces of thelight-emitting structure, and may also be formed on the upper surface ofthe etch-stop layer 621″.

The passivation layer 670″ may be formed of a silicon oxide, such asSiO₂, or a silicon nitride, such as Si_(x)N_(y), in order to perform aprotective function for the light-emitting structure. The passive layer670″ may have a thickness of approximately 0.1 to 2 μm and acorresponding refractive index of approximately 1.4 to 2.0. It may bedifficult for light from the active layer 612″ to be emitted to theoutside due to the difference in refractive index between thepassivation layer 670″ and air or a molding structure of a package. Inthis embodiment, the uneven structure is formed on the passivation layer670″ to thereby improve external light extraction efficiency. Inparticular, as shown in FIG. 36, when the uneven structure is formed ona region through which light emitted in a lateral direction of the lightactive layer 612″ passes, the amount of light emitted from the sides ofthe semiconductor light emitting device 600″ can be increased.Specifically, according to simulation results, a semiconductor lightemitting device according to this embodiment has increased lightextraction efficiency by approximately 5% or higher than a semiconductorlight emitting device having the same components except for thepassivation layer 670″ having the uneven structure. Though notnecessarily required in this embodiment, the uneven structure of thepassivation layer 670″ may also be formed on the upper surface of thefirst conductivity type semiconductor layer 611″ to thereby increaselight extraction efficiency in a vertical direction, and may also beformed on the side of the passivation layer 670″.

A semiconductor light emitting device according to another exemplaryembodiment of the invention will be described with FIGS. 37 through 57.

FIG. 37 is a perspective view schematically illustrating a semiconductorlight emitting device according to an exemplary embodiment of theinvention. FIG. 38 is a schematic plan view illustrating thesemiconductor light emitting device of FIG. 37 as viewed from the topside thereof. FIG. 39 is a schematic sectional view taken along the lineA-A′, as shown in FIG. 38, of the semiconductor light emitting device ofFIG. 37. Referring to FIGS. 37 through 39, in a semiconductor lightemitting device 800 according to this embodiment, a first conductivecontact layer 804 is formed on a conductive substrate 807, and alight-emitting structure, that is, a first conductivity typesemiconductor layer 803, an active layer 802, and a second conductivitytype semiconductor layer 801 are formed on the first conductive contactlayer 804. A high-resistance portion 808 is formed on the sides of thelight-emitting structure. As described below, the high-resistanceportion 808 may be formed by injecting ions into the sides of thelight-emitting structure. The first conductive contact layer 804 iselectrically insulated from the conductive substrate 807. To this end,an insulator 806 is interposed between the first conductive contactlayer 804 and the conductive substrate 807.

In this embodiment, the first and second conductivity type semiconductorlayers 803 and 801 may be p-type and n-type semiconductor layers,respectively, and may be formed of nitride semiconductors. Therefore, inthis embodiment, first conductive and second conductive may mean p-typeand n-type, respectively. The invention is not limited thereto, however.The first and conductive semiconductor layers 803 and 801 may satisfy anequation of AlxInyGa(1−x−y)N (where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1 aresatisfied), for example, GaN, AlGaN, and InGaN. The active layer 802,formed between the first and conductive semiconductor layers 803 and801, emits light having a predetermined amount of energy byelectron-hole recombination and may have a multiple quantum well (MQW)structure in which quantum well layers and quantum barrier layersalternate with each other. As for the multiple quantum well structure,an InGaN/GaN structure may be used.

The first conductive contact layer 804 may reflect light, emitted fromthe active layer 802, upward from the semiconductor light emittingdevice 800, that is, toward the second conductivity type semiconductorlayer 801. Further, the first conductive contact layer 804 and the firstconductivity type semiconductor layer 803 may form ohmic contacts. Inconsideration of these functions, the first conductive contact layer 804may contain Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, or Au. Here, thoughnot illustrated in detail, the first conductive contact layer 804 mayhave a dual or multi-layered structure to thereby increase reflectionefficiency. For example, the first conductive contact layer 804 may havea structure of Ni/Ag, Zn/Ag, Ni/Al, Zn/Al, Pd/Ag, Pd/Al, Ir/Ag, Ir/Au,Pt/Ag, Pt/Al, or Ni/Ag/Pt. In this embodiment, a portion of the firstconductive contact layer 804 may be exposed to the outside. As shown inthe drawings, the light-emitting structure may not be formed on theexposed portion. The exposed portion of the first conductive contactlayer 804 corresponds to an electrical connection portion to which anelectrical signal is applied. An electrode pad 805 may be formed on theexposed portion thereof.

As described below, the conductive substrate 807 serves as a supportthat holds the light-emitting structure during a laser-lift off processand may be formed of a material containing any one of Au, Ni, Al, Cu, W,Si, Se, and GaAs, for example, Si—Al alloys. Here, according to theselected material, the conductive substrate 807 may be formed usingplating or bonding. In this embodiment, the conductive substrate 807 iselectrically connected to the second conductivity type semiconductorlayer 801, so that an electrical signal may be applied to the secondconductivity type semiconductor layer 801 through the conductivesubstrate 807. To this end, as shown in FIGS. 39 and 40, conductive viasv that are extended from the conductive substrate 807 and are connectedto the second conductivity type semiconductor layer 801 need to beprovided.

The conductive vias v are internally connected to the secondconductivity type semiconductor layer 801. In order to reduce contactresistance, the number, shape, and pitch of the conductive vias v, and acontact area between the conductive vias v and the second conductivitytype semiconductor layer 801 may be appropriately determined. Here,since the conductive vias v need to be electrically insulated from theactive layer 802, the first conductivity type semiconductor layer 803,and the first conductive contact layer 804, the insulator 806 isinterposed therebetween. The insulator 806 may be formed of anysubstance having electrical insulation. However, since it is desirableto absorb the least amount of light, a silicon oxide or a siliconnitride, such as SiO₂, SiO_(x)N_(y), or Si_(x)N_(y), may be used to formthe insulator 806.

As described above, in this embodiment, the conductive substrate 807 isconnected to the second conductivity type semiconductor layer 801through the conductive vias v, and there is no need to separately forman electrode on the upper surface of the second conductivity typesemiconductor layer 801. Therefore, the amount of light, emitted upwardfrom the second conductivity type semiconductor layer 801, may beincreased. A light-emitting area will be reduced since the conductivevias v are formed in a portion of the active layer 802. However, inspite of that, light extraction efficiency will be significantlyimproved since an electrode is removed from the upper surface of thesecond conductivity type semiconductor layer 801. Meanwhile, it can beseen that the entire electrode arrangement of the second conductivitytype semiconductor layer 801 according to this embodiment is similar toa horizontal electrode structure rather than a vertical electrodestructure since an electrode is not disposed on the upper surface of thesecond conductivity type semiconductor layer 801. However, sufficientcurrent spreading effects can be ensured due to the conductive vias vformed inside the second conductivity type semiconductor layer 801.

The high-resistance portion 808 is formed along the edge of thelight-emitting structure, and protects the light-emitting structure,particularly, the active layer 802 against the outside environment,thereby increasing the electrical reliability of the device. Since theactive layer 802, exposed to the outside, may serve as a current leakagepath, during the operation of the semiconductor light emitting device800, the high-resistance portion 808 with relatively high electricalresistance, is formed along the side of the light-emitting structure,thereby preventing a current leakage. Here, the high-resistance portion808 may be formed by ion implantation. Specifically, when ions,accelerated by a particle accelerator, are implanted into thelight-emitting structure, the crystals of the semiconductor layersforming the light-emitting structure are damaged to thereby increaseresistance. Here, since the implanted ions can be restored by heattreatment, ions having a large particle size may be used so that theions are not restored a general heat treatment temperature ofsemiconductor layers. For example, ions of atoms, such as Ar, C, N, Kr,Xe, Cr, O, Fe, and Ti, may be implanted into the light-emittingstructure.

FIGS. 40 and 41 are cross-sectional views schematically illustratingmodified embodiments of the semiconductor light emitting device of FIG.37. First, a semiconductor light emitting device 800-1, as shown in FIG.40, is formed in such a manner that the sides of a light-emittingstructure are inclined relative to the first conductive contact layer804. Specifically, the sides of the light-emitting structure areinclined toward the upper part of the light-emitting structure. Asdescribed below, the inclined light-emitting structure may be naturallyobtained through a process of etching the light-emitting structure toexpose the first conductive contact layer 804. A semiconductor lightemitting device 800-2, as shown in FIG. 41, has unevenness formed on theupper surface of the light-emitting structure of the embodiment,described with reference to FIG. 40, and specifically, the upper surfaceof the second conductivity type semiconductor layer 801. This unevennessmay be appropriately provided using dry etching or wet etching. Here, anuneven structure having facets of irregular sizes, shapes, and periodsmay be provided by wet etching. This uneven structure may increase thepossibility that light, made incident in a direction of the active layer802, is emitted to the outside. The modified embodiments, which havebeen described with reference to FIGS. 40 and 41, may be applied toother embodiments of FIGS. 42 through 44.

FIG. 42 is a cross-sectional view schematically illustrating asemiconductor light emitting device according to another exemplaryembodiment of the invention. Referring to FIG. 42, like theabove-described embodiment, in a semiconductor light emitting device 900according to this embodiment, a first conductive contact layer 904 isformed on a conductive substrate 907, and a light-emitting structure,that is, a first conductivity type semiconductor layer 903, an activelayer 902, and a second conductivity type semiconductor layer 901 areprovided on the first conductive contact layer 904. A high-resistanceportion 908 is formed on the edge of the light-emitting structure by ionimplantation. The structural difference between this embodiment and theabove-described embodiments is that the conductive substrate 907 iselectrically connected to the first conductivity type semiconductorlayer 903 rather than the second conductivity type semiconductor layer901. Therefore, the first conductive contact layer 904 is notnecessarily required. Here, the first conductivity type semiconductorlayer 903 and the conductive substrate 907 may come into direct contactwith each other.

Conductive vias v, internally connected to the second conductivity typesemiconductor layer 901, pass through the active layer 902, the firstconductivity type semiconductor layer 903, and the first conductivecontact layer 904, and are connected to the second conductive electrode909. The second conductive electrode 909 has an electrical connectionportion that is extended from the conductive vias v toward the side ofthe light-emitting structure and is exposed to the outside. An electrodepad 905 may be formed on the electrical connection portion. Here, aninsulator 906 is formed to electrically insulate the second conductiveelectrode 909 and the conductive vias v from the active layer 902, thefirst conductivity type semiconductor layer 903, the first conductivecontact layer 904, and the conductive substrate 907.

FIG. 43 is a plan view schematically illustrating a semiconductor lightemitting device according to another exemplary embodiment to theinvention. FIG. 44 is a schematic sectional view taken along the lineB-B′ of the semiconductor light emitting device of FIG. 43. As describedwith reference to FIGS. 37 through 39, in a semiconductor light emittingdevice 800′ according to this embodiment, a first conductive contactlayer 804′ is formed on a conductive substrate 807′, and alight-emitting structure, that is, a first conductivity typesemiconductor layer 803′, an active layer 802′, and a secondconductivity type semiconductor layer 801′ are formed on the firstconductive contact layer 804′. A high-resistance portion 808′ is formedon the edge of the light-emitting structure by ion implantation.Furthermore, the first conductive contact layer 804′ is electricallyinsulated from the conductive substrate 807′. To this end, an insulator806′ is interposed between the first conductive contact layer 804′ andthe conductive substrate 807′. In this embodiment, the light-emittingstructure is divided into a plurality of structures on the conductivesubstrate 807′. The light-emitting structure, divided into the pluralityof structures, may increase light-scattering effects. Therefore, animprovement in the light extraction efficiency may be expected. In orderto ensure a sufficient outside area, as shown in FIG. 43, thelight-emitting structure may have a hexagonal shape. However, theinvention is not limited thereto. Here, an increase in spacing betweenthe divided structures of the light-emitting structure may reduce thearea of the active layer 802′, which may cause a reduction in luminanceefficiency. Therefore, the divided structures of the light-emittingstructure may be brought into as close a contact as possible. Asdescribed above, when an etching process is performed in order to dividethe light-emitting structure, the sides of the light-emitting structureneed to be protected. A high-resistance portion 808′ may be formed onthe sides of each of the divided structures of the light-emittingstructure by ion implantation.

Hereinafter, a process of manufacturing the semiconductor light emittingdevice having the above-described configuration will be described.

FIGS. 45 through 53 are cross-sectional views illustrating the processflow of a method of manufacturing a semiconductor light emitting deviceaccording to this embodiment of the invention. Specifically, a method ofmanufacturing a semiconductor light emitting device having theconfiguration, having been described with reference to FIGS. 37 to 39,will be described.

First, as shown in FIG. 45, the second conductivity type semiconductorlayer 801, the active layer 802, and the first conductivity typesemiconductor layer 803 are sequentially grown on a semiconductor growthsubstrate B using a semiconductor layer growing process, such as MOCVD,MBE, or HVPE, thereby manufacturing a light-emitting structure. As forthe semiconductor growth substrate B, a substrate, formed of SiC,MgAl₂O₄, MgO, LiAlO₂, LiGaO₂, or GaN may be used. Here, sapphire is acrystal having Hexa-Rhombo R3c symmetry (Hexa-Rhombo R3c) and has alattice constant of 13.001 Å along the c-axis and a lattice constant of4.758 Å along the a-axis. Orientation planes of the sapphire include theC(0001) plane, the A(1120) plane, and the R(1102) plane. Here, sincenitride thin films are relatively easily grown on the C-plane sapphiresubstrate, which is stable at high temperatures, the C-plane sapphiresubstrate is widely used as a nitride growth substrate.

As shown in FIG. 46, the first conductive contact layer 804 is formed onthe first conductivity type semiconductor layer 803. The firstconductive contact layer 804 may contain Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg,Zn, Pt, or Au in consideration of light reflection function and ohmiccontacts, formed together with first conductivity type semiconductorlayer 803, and may be formed using sputtering or deposition, both ofwhich are known in the art. Then, as shown in FIG. 47, recesses areformed in the first conductive contact layer 804 and the light-emittingstructure. Specifically, in subsequent operations, the recesses arefilled with conductive materials to thereby form conductive viasconnected to the second conductivity type semiconductor layer 801. Therecesses pass through the first conductive contact layer 804, the firstconductivity type semiconductor layer 803, and the active layer 802. Thesecond conductivity type semiconductor layer 801 is exposed as thebottom surfaces of the recesses. The operation of forming recesses,shown in FIG. 47, may be performed using an etching process known in therelated art, for example, ICP-RIE.

Then, as shown in FIG. 48, a material, such as SiO₂, SiO_(x)N_(y), orSi_(x)N_(y), is deposited to form the insulator 806 so that theinsulator 806 covers the top of the first conductive contact layer 804and the side walls of the grooves. Here, since the second conductivitytype semiconductor layer 801 corresponding to the bottom surfaces of therecesses needs to be at least partially exposed, the insulator 806 maybe formed not to completely cover the bottom surfaces of the grooves.

Then, as shown in FIG. 49, conductive materials are formed within therecesses and on the insulator 806 to thereby form the conductive vias vand the conductive substrate 807, so that the conductive substrate 807is connected to the conductive vias v making contact with the secondconductivity type semiconductor layer 801. The conductive substrate 807may include any one of the materials, such as Au, Ni, Al, Cu, W, Si, Se,and GaAs, by plating, sputtering, or deposition. Here, the conductivevias v and the conductive substrate 807 may be formed of the samematerial. Alternatively, when the conductive vias v and the conductivesubstrate 807 may be formed of different materials from each other, theymay be formed using separate processes. For example, after theconductive vias v are formed by deposition, the conductive substrate 807may be previously prepared and bonded to the light-emitting structure.

Then, as shown in FIG. 50, the semiconductor growth substrate B isremoved to expose the second conductivity type semiconductor layer 801.Here, the semiconductor growth substrate B may be removed using laserlift-off or chemical lift-off. FIG. 50 is a view, rotated by 180degrees, of FIG. 49, in which the semiconductor growth substrate B isremoved.

Then, as shown in FIG. 51, the light-emitting structure, that is, thefirst conductivity type semiconductor layer 803, the active layer 802,and the second conductivity type semiconductor layer 801 are partiallyremoved to expose the first conductive contact layer 804, so that anelectrical signal can be applied through the exposed first conductivecontact layer 804. Furthermore, as described above, the operation ofremoving the light-emitting structure may be used to divide thelight-emitting structure into a plurality of structures. Though notshown in the drawing, an operation of forming an electrode pad on theexposed portion of the first conductive contact layer 804 may be furtherperformed. In order to expose the first conductive contact layer 804,the light-emitting structure may be etched using ICP-RIE or the like.Here, in order to prevent the material forming the first conductivecontact layer 804 from moving to the side of the light-emittingstructure and being attached thereto, as shown in FIG. 52, an etch-stoplayer 809 may be previously formed inside the light-emitting structure.

Then, as shown in FIG. 53, the high-resistance portion 808 may be formedon the side surfaces of the light-emitting structure. Thehigh-resistance portion 808 corresponds to a region where crystals ofthe semiconductor layer forming the light-emitting structure are damagedby ions implanted to the side thereof. Here, since the implanted ionsmay be restored by heat treatment, ions having a large particle size maybe used so that the ions are not restored a general heat treatmenttemperature of the semiconductor layer. For example, ions of atoms, suchas Ar, C, N, Kr, Xe, Cr, O, Fe, and Ti, may be implanted into thelight-emitting structure.

FIGS. 54 through 57 are cross-sectional views illustrating the processflow of a method of manufacturing a semiconductor light emitting deviceaccording to another exemplary embodiment of the invention, andspecifically, a method of manufacturing the semiconductor light emittingdevice, as shown in FIG. 42. Here, the operations, having been describedwith FIGS. 45 through 47, may be directly applied to this embodiment.Hereinafter, subsequent operations to the operation of forming recessesin the first conductive contact layer 904 and the light-emittingstructure will be described.

First, as shown in FIG. 54, a material, such as SiO₂, SiO_(x)N_(y), orSi_(x)N_(y), is deposited to form the insulator 906 in order to coverthe upper part of the first conductive contact layer 904 and the sidewalls of the recesses. Here, the insulator 906 may be referred to as afirst insulator to differentiate the first insulator from an insulatorto be formed to cover the second conductive electrode 909 in subsequentoperations. Unlike the above-described embodiments, the insulator 906 isnot formed on the entire upper surface of the first conductive contactlayer 904 in this embodiment, so that the conductive substrate 907 andthe first conductive contact layer 904 come into contact with eachother. That is, the insulator 906 may be formed in consideration of aportion of the upper surface of the first conductive contact layer 904,and specifically, a region where the second conductive electrode 909,connected to the second conductivity type semiconductor layer 901, isformed.

Then, as shown in FIG. 55, conductive materials are formed within therecesses and on the insulator 906 to thereby form the second conductiveelectrode 909, so that the second conductive electrode 909 includes theconductive vias v connected to the second conductivity typesemiconductor layer 901. In this operation, the insulator 906 ispreviously formed at a position where the second conductive electrode909 will be formed, thereby forming the second conductive electrode 909according to the insulator 960. In particular, the second conductiveelectrode 909 may be exposed to the outside and be extended in ahorizontal direction from the conductive vias v so as to serve as anelectrical connection portion.

Then, as shown in FIG. 56, the insulator 906 is formed to cover thesecond conductive electrode 909, and the conductive substrate 907 isformed thereon so as to be electrically connected to the firstconductive contact layer 904. Here, the insulator 906, formed in thisoperation, may be referred to as a second insulator. The earlierinsulator and this insulator 906 may form a single insulating structure.In this operation, the second conductive electrode 909 may beelectrically insulated from the first conductive contact layer 904 andthe conductive substrate 907. Then, as shown in FIG. 57, the secondconductivity type semiconductor layer 901 is removed to expose thesemiconductor growth substrate B. Though not shown in the drawings, anoperation of partially removing the light-emitting structure to exposethe second conductive electrode 909 and an operation of forming thehigh-resistance portion 908 on the side surfaces of the light-emittingstructure by ion implantation may be performed using the above-describedoperations.

A semiconductor light emitting device will according to anotherexemplary embodiment of the invention will be described with referenceto FIGS. 58 through 77.

FIG. 58 is a perspective view schematically illustrating a semiconductorlight emitting device according to this embodiment. FIG. 59 is aschematic plan view illustrating a second conductivity typesemiconductor layer of the semiconductor light emitting device as viewedfrom top of FIG. 58. FIG. 60 is a schematic sectional view taken alongthe line A-A′, of FIG. 59, of the semiconductor light emitting device ofFIG. 58. In a semiconductor light emitting device 1000 according to thisembodiment, a first conductive contact layer 1004 is formed on aconductive substrate 1007, and a light-emitting structure, that is, afirst conductivity type semiconductor layer 1003, an active layer 1002,and a first conductivity type semiconductor layer 1001, are formed onthe first conductive contact layer 1004. An undoped semiconductor layer1008 is formed on the first conductivity type semiconductor layer 1001.Unevenness is provided on the upper surface of the undoped semiconductorlayer 1008, thereby increasing the external extraction efficiency oflight emitted from the active layer 1002. The first conductive contactlayer 1004 is electrically insulated from the conductive substrate 1007.To this end, an insulator 1006 is interposed between the firstconductive contact layer 1004 and the conductive substrate 1007.

In this embodiment, the first and second conductivity type semiconductorlayers 1003 and 1001 may be p-type and n-type semiconductor layers,respectively, and may be formed of nitride semiconductors. Therefore, inthis embodiment, first conductive and second conductive may mean p-typeand n-type, respectively. However, the invention is not limited thereto.The first and second conductivity type semiconductor layers 1003 and1001 may satisfy an equation of Al_(x)In_(y)Ga_((1-x-y))N (where 0≦x≦1,0≦y≦1, and 0≦x+y≦1 are satisfied), for example, GaN, AlGaN, and InGaN.The active layer 1002, formed between the first and conductivesemiconductor layers 1003 and 1001, emits light having a predeterminedamount of energy by electron-hole recombination and may have a multiplequantum well (MQW) structure in which quantum well layers and quantumbarrier layers alternate with each other. As for the multiple quantumwell structure, an InGaN/GaN structure may be used.

The first conductive contact layer 1004 may reflect light, emitted fromthe active layer 1002, upward from the semiconductor light emittingdevice 1000, that is, toward the second conductivity type semiconductorlayer 1001. Further, the first conductive contact layer 1004 and thefirst conductivity type semiconductor layer 1003 may form ohmiccontacts. In consideration of these functions, the first conductivecontact layer 1004 may contain Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt,or Au. Here, though not illustrated in detail, the first conductivecontact layer 1004 may have a dual or multi-layered structure to therebyincrease reflection efficiency. For example, the first conductivecontact layer 1004 may have a structure of Ni/Ag, Zn/Ag, Ni/Al, Zn/Al,Pd/Ag, Pd/Al, Ir/Ag, Ir/Au, Pt/Ag, Pt/Al, or Ni/Ag/Pt. In thisembodiment, a portion of the first conductive contact layer 1004 may beexposed to the outside. As shown in the drawings, the light-emittingstructure may not be formed on the exposed portion. The exposed portionof the first conductive contact layer 1004 corresponds to an electricalconnection portion to which an electrical signal is applied. Anelectrode pad 1005 may be formed on the exposed portion thereof.

As described below, the conductive substrate 1007 serves as a supportthat holds the light-emitting structure during a laser-lift off processand may be formed of a material containing any one of Au, Ni, Al, Cu, W,Si, Se, and GaAs, for example, Si—Al alloys. Here, according to theselected material, the conductive substrate 1007 may be formed usingplating or bonding. In this embodiment, the conductive substrate 1007 iselectrically connected to the second conductivity type semiconductorlayer 1001, so that an electrical signal may be applied to the secondconductivity type semiconductor layer 1001 through the conductivesubstrate 1007. To this end, as shown in FIGS. 59 and 60, conductivevias v that are extended from the conductive substrate 1007 and areconnected to the second conductivity type semiconductor layer 1001 needto be provided.

The conductive vias v are internally connected to the secondconductivity type semiconductor layer 1001. In order to reduce contactresistance, the number, shape, and pitch of the conductive vias v, and acontact area between the conductive vias v and the second conductivitytype semiconductor layer 1001 may be appropriately determined. Here,since the conductive vias v need to be electrically insulated from theactive layer 1002, the first conductivity type semiconductor layer 1003,and the first conductive contact layer 1004, the insulator 1006 isinterposed therebetween. The insulator 1006 may be formed of anysubstance having electrical insulation. However, since it is desirableto absorb the least amount of light, a silicon oxide or a siliconnitride, such as SiO₂, SiO_(x)N_(y), or Si_(x)N_(y), may be used to formthe insulator 1006.

As described above, in this embodiment, the conductive substrate 1007 isconnected to the second conductivity type semiconductor layer 1001through the conductive vias v, and there is no need to separately forman electrode on the upper surface of the second conductivity typesemiconductor layer 1001. Therefore, the amount of light, emitted upwardfrom the second conductivity type semiconductor layer 1001, may beincreased. A light-emitting area will be reduced since the conductivevias v are formed in a portion of the active layer 1002. However, inspite of that, light extraction efficiency will be significantlyimproved since an electrode is removed from the upper surface of thesecond conductivity type semiconductor layer 1001. Meanwhile, it can beseen that the entire electrode arrangement of the second conductivitytype semiconductor layer 1001, according to this embodiment, is similarto a horizontal electrode structure rather than a vertical electrodestructure, since an electrode is not disposed on the upper surface ofthe second conductivity type semiconductor layer 1001. However,sufficient current spreading effects can be ensured due to theconductive vias v formed inside the second conductivity typesemiconductor layer 1001.

The undoped semiconductor layer 1008 is formed on the upper surface ofthe second conductivity type semiconductor layer 1001. As describedbelow, the undoped semiconductor layer 1008 is employed as a bufferlayer before the growth of the semiconductor layers forming thelight-emitting structure. Here, “undoped” means a state in which asemiconductor layer does not undergo a separate impurity-doping process.When a semiconductor layer having a predetermined level of impurityconcentration, for example, if a gallium nitride having a concentrationof is grown using MOCVD, Si having a concentration of approximately 10¹⁶to 10¹⁸/cm³, being used as a dopant, may be contained without intention.In this embodiment, since an electrode does not have to be formed on theupper surface of the second conductivity type semiconductor layer 1001,the undoped semiconductor layer 1008 is not removed. Therefore, theundoped semiconductor layer 1008 may be formed to cover the entire uppersurface of the second conductivity type semiconductor layer 1001.Further, an uneven structure is formed on the undoped semiconductorlayer 1008, thereby increasing the possibility that light, made incidentin the direction of the active layer 1002, is emitted to the outside. Inthis embodiment, the description has been made to a case in whichunevenness is only applied to the undoped semiconductor layer 1008.However, depending on etching conditions, unevenness may further beformed on a portion of the second conductivity type semiconductor layer1001.

When the undoped semiconductor layer 1008 is removed, and an unevenstructure is then formed on the second conductivity type semiconductorlayer 1001, a part of the second conductivity type semiconductor layer1001 may be damaged. In particular, if an unevenness forming process isnot accurately controlled, the uniform thickness of the secondconductivity type semiconductor layer 1001 may not be maintained,depending on products. Therefore, like this embodiment, the electrodeconnection structure of the second conductivity type semiconductor layer1001 is formed at the lower part thereof through the inside of thesecond conductivity type semiconductor layer 1001, these problems may besolved by forming the uneven structure on the undoped semiconductorlayer 1008 not being removed.

FIGS. 61 and 62 are cross-sectional views schematically illustrating amodified embodiment of the semiconductor light emitting device of FIG.58. First, a light emitting device 1000-1, as shown in FIG. 61, isformed in such a manner that the side surfaces of a light-emittingstructure are inclined relative to the first conductive contact layer1004. Specifically, the side surfaces of the light-emitting structureare inclined toward the upper part of the light-emitting structure. Asdescribed below, the inclined light-emitting structure may be naturallyobtained through a process of etching the light-emitting structure toexpose the first conductive contact layer 1004. A semiconductor lightemitting device 1000-2, as shown in FIG. 61, further includes apassivation layer 1009 in order to cover the side surfaces of thelight-emitting structure of FIG. 61. The passivation layer 1009 protectsthe light-emitting structure, and particularly, the active layer 1002against the outside environment. The passivation layer 1009 may beformed of a silicon oxide or a silicon nitride, such as SiO₂,SiO_(x)N_(y), or Si_(x)N_(y), and may have a thickness of approximately0.1 to 2 μm.

Since the active layer 1002, exposed to the outside, may serve as acurrent leakage path, during the operation of the semiconductor lightemitting device 1000, this problem can be prevented by forming thepassivation layer 1009 on the side surfaces of the light-emittingstructure. Considering this aspect, as shown in FIG. 62, the passivationlayer 1009 may further be extended to the exposed upper surface of thefirst conductive contact layer 1004. The modified embodiments, havingbeen described with reference to FIGS. 61 and 62, may be applied toother embodiments of FIGS. 63 and 64.

FIG. 63 is a cross-sectional view schematically illustrating asemiconductor light emitting device according to another exemplaryembodiment of the invention. Referring to FIG. 63, like theabove-described embodiment, in a semiconductor light emitting device1100 according to this embodiment, a first conductive contact layer 1104is formed on a conductive substrate 1107, and a light-emittingstructure, that is, a first conductivity type semiconductor layer 1103,an active layer 1102, and a second conductivity type semiconductor layer1101 are formed on the first conductive contact layer 1104. An undopedsemiconductor layer 1108 is formed on the first conductivity typesemiconductor layer 1101. Unevenness is provided on the upper surface ofthe undoped semiconductor layer 1108. The first conductive contact layer1104 is electrically insulated from the conductive substrate 1107. Tothis end, an insulator 1106 is interposed between the first conductivecontact layer 1104 and the conductive substrate 1107.

Unlike the above-described embodiments, in which the electricalconnection portion of the first conductive contact layer 1104 is formedat a position corresponding to the edge of the light-emitting structureas viewed from the top of the light-emitting structure, in thisembodiment, the electrical connection portion of the first conductivecontact layer 1104 is formed at a position corresponding to the centerof the light-emitting structure as viewed from the top of thelight-emitting structure. As such, the position of the exposed region ofthe first conductive contact layer 1104 may be changed upon necessity inthis invention. An electrode pad 1105 may be formed on the electricalconnection portion of the first conductive contact layer 1104.

FIG. 64 is a cross-sectional view schematically illustrating asemiconductor light emitting device according to another exemplaryembodiment of the invention. Referring to FIG. 64, in a semiconductorlight emitting device 1200 according to this embodiment, a firstconductive contact layer 1204 is formed on a conductive substrate 1207,and a light-emitting structure, that is, a first conductivity typesemiconductor layer 1203, an active layer 1202, and a secondconductivity type semiconductor layer 1201 are formed on the firstconductive contact layer 1204. An undoped semiconductor layer 1208 isformed on the light emitting structure, that is, on the firstconductivity type semiconductor layer 1201. An uneven structure isformed on the upper surface of the undoped semiconductor layer 1208. Thestructural difference between the semiconductor light emitting device1200 according to this embodiment and the above-described embodiments isthat the conductive substrate 1207 is electrically connected to thefirst conductivity type semiconductor layer 1203 rather than the secondconductivity type semiconductor layer 1201. Therefore, the firstconductive contact layer 1204 is not necessarily required. In this case,the first conductivity type semiconductor layer 1203 may come intodirect contact with the conductive substrate 1207.

Conductive vias v, which are internally connected to the secondconductivity type semiconductor layer 1201, pass through the activelayer 1202, the first conductivity type semiconductor layer 1203, andthe first conductive contact layer 1204, and are connected to the secondconductive electrode 1209. The second conductive electrode 1209 has anelectrical connection portion that is extended from the conductive viasv toward the side of the light-emitting structure and is exposed to theoutside. An electrode pad 1205 may be formed on the electricalconnection portion. Here, an insulator 1206 is formed to electricallyinsulate the second conductive electrode 1209 and the conductive vias vfrom the active layer 1202, the first conductivity type semiconductorlayer 1203, the first conductive contact layer 1204, and the conductivesubstrate 1207.

Hereinafter, a process of manufacturing the semiconductor light emittingdevice having the above-described configuration will be described.

FIGS. 65 through 73 are cross-sectional views illustrating the processflow of a method of manufacturing a semiconductor light emitting deviceaccording to this embodiment of the invention. Specifically, a method ofmanufacturing a semiconductor light emitting device having theconfiguration, having been described with reference to FIGS. 58 to 60,will be described.

First, as shown in FIG. 65, the second conductivity type semiconductorlayer 1001, the active layer 1002, and the first conductivity typesemiconductor layer 1003 are sequentially grown on a semiconductorgrowth substrate B using a semiconductor layer growing process, such asMOCVD, MBE, or HVPE, thereby manufacturing a light-emitting structure.Here, as described above, in terms of configuration, the light-emittingstructure is defined as a configuration having the second conductivitytype semiconductor layer 1001, the active layer 1002, and the firstconductivity type semiconductor layer 1003, while in terms of growth andetching, the buffer layer 1008 can be considered a component forming thelight-emitting structure. Therefore, hereinafter, the light-emittingstructure will be defined as a configuration having the buffer layer1008, the second conductivity type semiconductor layer 1001, the activelayer 1002, and the first conductivity type semiconductor layer 1003.

As for the semiconductor growth substrate B, a substrate, formed of SiC,MgAl₂O₄, MgO, LiAlO₂, LiGaO₂, or GaN may be used. Here, sapphire is acrystal having Hexa-Rhombo R3c symmetry (Hexa-Rhombo R3c) and has alattice constant of 13.001 Å along the c-axis and a lattice constant of4.758 Å along the a-axis. Orientation planes of the sapphire include theC(0001) plane, the A(1120) plane, and the R(1102) plane. Here, sincenitride thin films are relatively easily grown on the C-plane sapphiresubstrate, which is stable at high temperatures, the C-plane sapphiresubstrate is widely used as a nitride growth substrate. As describedabove, as for the buffer layer 1008, an undoped semiconductor layer,formed of a nitride, may be used to prevent the lattice defects of thelight-emitting structure to be formed thereon.

Then, as shown in FIG. 66, the first conductive contact layer 1004 isformed on the first conductivity type semiconductor layer 1003. Thefirst conductive contact layer 1004 may contain Ag, Ni, Al, Rh, Pd, Ir,Ru, Mg, Zn, Pt, or Au in consideration of light reflection function andohmic contacts, formed together with first conductivity typesemiconductor layer 1003, and may be formed using sputtering ordeposition, which both of which are known in the art. Then, as shown inFIG. 67, recesses are formed in the first conductive contact layer 1004and the light-emitting structure. Specifically, in subsequentoperations, the recesses are filled with conductive materials to therebyform conductive vias connected to the second conductivity typesemiconductor layer 1001. The recesses pass through the first conductivecontact layer 1004, the first conductivity type semiconductor layer1003, and the active layer 1002. The second conductivity typesemiconductor layer 1001 is exposed as the bottom surface of therecesses. The operation of forming recesses, shown in FIG. 67, may beperformed using an etching process known in the related art, forexample, ICP-RIE.

Then, as shown in FIG. 68, a material, such as SiO₂, SiO_(x)N_(y), orSi_(x)N_(y), is deposited to form the insulator 1006 so that theinsulator 1006 covers the top of the first conductive contact layer 1004and the side walls of the grooves. Here, since the second conductivitytype semiconductor layer 1001 corresponding to the bottom surfaces ofthe recesses needs to be at least partially exposed, the insulator 1006may be formed so as not to completely cover the bottom surfaces of thegrooves.

Then, as shown in FIG. 69, conductive materials are formed within therecesses and on the insulator 1006 to thereby form the conductive vias vand the conductive substrate 1007, so that the conductive substrate 1007is connected to the conductive vias v making contact with the secondconductivity type semiconductor layer 1001. The conductive substrate1007 may include any one of the materials, such as Au, Ni, Al, Cu, W,Si, Se, and GaAs, by any one of plating, sputtering, and deposition.Here, the conductive vias v and the conductive substrate 1007 may beformed of the same material. Alternatively, when the conductive vias vand the conductive substrate 1007 may be formed of different materialsfrom each other, they may be formed using separate processes. Forexample, after the conductive vias v are formed by deposition, theconductive substrate 1007 may be previously prepared and bonded to thelight-emitting structure.

As shown in FIG. 70, the semiconductor growth substrate B is removed toexpose the buffer layer 1008. Here, the semiconductor growth substrate Bmay be removed using laser lift-off or chemical lift-off. FIG. 70 is aview, rotated by 180 degrees, of FIG. 68, in which the semiconductorgrowth substrate B is removed.

Then, as shown in FIG. 71, the light-emitting structure, that is, thebuffer layer 1008, the first conductivity type semiconductor layer 1003,the active layer 1002, and the second conductivity type semiconductorlayer 1001 are partially removed to expose the first conductive contactlayer 1004, so that an electrical signal can be applied through theexposed first conductive contact layer 1004. Though not shown in thedrawings, an operation of forming an electrode pad on the exposedportion of the first conductive contact layer 1004 may be furtherperformed. In order to expose the first conductive contact layer 1004,the light-emitting structure may be etched using ICP-RIE or the like.Here, in order to prevent the material, forming the first conductivecontact layer 1004, from moving to the side of the light-emittingstructure and being attached thereto, as shown in FIG. 72, an etch-stoplayer 1010 may be previously formed inside the light-emitting structure.Furthermore, as a more reliable insulating structure, after etching thelight-emitting structure, the passivation layer 1009, as shown in FIG.62, may be formed on the side surfaces of the light-emitting structure.

Then, as shown in FIG. 73, an uneven structure is formed on the bufferlayer 1008. Here, unevenness may be mainly formed on the upper surfaceof the buffer layer 1008 that is exposed by removing the semiconductorgrowth substrate B. This uneven structure may increase light extractionefficiency. Here, the uneven structure may be formed using dry or wetetching. Here, an uneven structure having facets of irregular sizes,shapes, and periods may be provided by wet etching. In this embodiment,an electrical signal is smoothly applied to the first conductivity typesemiconductor layer 1001 without removing the buffer layer 1008 with lowelectrical conductivity. By forming the uneven structure on the bufferlayer 1008, the uniform thickness of the first conductivity typesemiconductor layer 1001 can be ensured.

FIGS. 74 through 77 are cross-sectional views illustrating the processflow of a method of manufacturing a semiconductor light emitting deviceaccording to another exemplary embodiment of the invention.Specifically, a method of manufacturing the semiconductor light emittingdevice having the configuration, having been described with reference toFIG. 64, will be described. The operations, having been described withreference to FIGS. 65 through 67, may be directly applied to thisembodiment. Hereinafter, operations subsequent to the operation offorming the recesses in the first conductive contact layer 1204 and thelight-emitting structure will be described.

First, as shown in FIG. 74, a material, such as SiO₂, SiO_(x)N_(y), orSi_(x)N_(y), is deposited to form the insulator 1206 in order to coverthe upper part of the first conductive contact layer 1204 and the sidewalls of the recesses. Here, the insulator 1206 may be referred to as afirst insulator to differentiate the first insulator from an insulatorto be formed to cover the second conductive electrode 1209 in subsequentoperations. Unlike the above-described embodiments, the insulator 1206is not formed on the entire upper surface of the first conductivecontact layer 1204 in this embodiment, so that the conductive substrate1207 and the first conductive contact layer 1204 come into contact witheach other. That is, the insulator 1206 may be formed in considerationof a portion of the upper surface of the first conductive contact layer1204, and specifically, a region in which the second conductiveelectrode 1209, connected to the second conductivity type semiconductorlayer 1201, is formed.

Then, as shown in FIG. 75, conductive materials are formed within therecesses and on the insulator 1206 to thereby form the second conductiveelectrode 1209, so that the second conductive electrode 1209 includesthe conductive vias v connected to the second conductivity typesemiconductor layer 1201. In this operation, the insulator 1206 ispreviously formed at a position where the second conductive electrode1209 will be formed, thereby forming the second conductive electrode1209 according to the insulator 1206. In particular, the secondconductive electrode 1209 is exposed to the outside and is extended in ahorizontal direction from the conductive vias v so as to serve as anelectrical connection portion.

Then, as shown in FIG. 76, the insulator 1206 is formed to cover thesecond conductive electrode 1209, and the conductive substrate 1207 isformed thereon so as to be electrically connected to the firstconductive contact layer 1204. Here, the insulator 1206, formed in thisoperation, may be referred to as a second insulator. The earlierinsulator and the insulator 1206 may form a single insulating structure.In this operation, the second conductive electrode 1209 may beelectrically insulated from the first conductive contact layer 1204 andthe conductive substrate 1207. Then, as shown in FIG. 77, the secondconductivity type semiconductor layer 1201 is removed to expose thesemiconductor growth substrate B. Though not shown in the drawings, anoperation of partially removing the light-emitting structure to exposethe second conductive electrode 1209 and an operation of forming thehigh-resistance portion 1208 along the side surfaces of thelight-emitting structure by ion implantation may be then performed usingthe above-described operations.

A semiconductor light emitting device according to another exemplaryembodiment of the invention will now be described with reference toFIGS. 78 through 91.

FIG. 78 is a cross-sectional view schematically illustrating asemiconductor light emitting device according to this embodiment. FIG.79 is a circuit diagram illustrating the semiconductor light emittingdevice of FIG. 78. Referring to FIG. 78, in a semiconductor lightemitting device 1300 according to this embodiment, a plurality oflight-emitting structures C1 and C2 are formed on a substrate 1306 whilethe light-emitting structures C1 and C2 are electrically connected toeach other. Here, two light-emitting structures are referred to as firstand second light-emitting structures C1 and C2, respectively. The firstand second light-emitting structures C1 and C2 each have a firstconductivity type semiconductor layer 1303, an active layer 1302, and asecond conductivity type semiconductor layer 1301 stacked upon eachother in a sequential manner on the substrate 1306, and have first andsecond electrical connection portions 1304 and 1307, respectively, inorder to provide an electrical connection therebetween.

The first electrical connection portion 1304 is formed under the firstconductivity type semiconductor layer 1303, and may provide ohmiccontacts and light reflection function in addition to electricalconnections. The second electrical connection portion 1307 may beelectrically connected to the second conductivity type semiconductorlayer 1301 and have conductive vias v passing through the firstelectrical connection portion 1304, the first conductivity typesemiconductor layer 1303, and the active layer 1302 so as to beconnected to the second conductivity type semiconductor layer 1301. Thesecond connection portion of the first light-emitting structure C1, thatis, the conductive vias v and the first electrical connection portion1304 of the second light-emitting structure C2 are electricallyconnected to each other through the substrate 1306. To this end, thesubstrate 1306 is formed of a material having electrical conductivity.As the substrate 1306 has this electrical connection structure, thesemiconductor light emitting device 1300 can be operated even thoughexternal AC power is applied.

In this embodiment, the first and second conductivity type semiconductorlayers 1303 and 1301 may be p-type and n-type semiconductor layers,respectively, and may be formed of nitride semiconductors. Therefore, inthis embodiment, first conductive and second conductive may mean p-typeand n-type, respectively. The invention is not limited thereto, however.The first and second conductivity type semiconductor layers 1303 and1301 may satisfy an equation of Al_(x)In_(y)Ga_((1-x-y))N (where 0≦x≦1,0≦y≦1, and 0≦x+y≦1 are satisfied), for example, GaN, AlGaN, and InGaN.The active layer 1302, formed between the first and conductivesemiconductor layers 1303 and 1301, emits light having a predeterminedamount of energy by electron-hole recombination and may have a multiplequantum well (MQW) structure in which quantum well layers and quantumbarrier layers alternate with each other. As for the multiple quantumwell structure, an InGaN/GaN structure may be used.

As described above, the first conductive contact layer 1304 may reflectlight, emitted from the active layer 1302, upward from the semiconductorlight emitting device 1300, that is, toward the second conductivity typesemiconductor layer 1301. Further, the first conductive contact layer1304 and the first conductivity type semiconductor layer 1303 may formohmic contacts. In consideration of these functions, the firstconductive contact layer 1304 may contain Ag, Ni, Al, Rh, Pd, Ir, Ru,Mg, Zn, Pt, or Au. Here, though not illustrated in detail, the firstconductive contact layer 1304 may have a dual or multi-layered structureto thereby increase reflection efficiency. For example, the firstconductive contact layer 1304 may have a structure of Ni/Ag, Zn/Ag,Ni/Al, Zn/Al, Pd/Ag, Pd/Al, Ir/Ag, Ir/Au, Pt/Ag, Pt/Al, or Ni/Ag/Pt.

When manufacturing the semiconductor light emitting device 1300, thesubstrate 1306 serves as a support that holds the first and secondlight-emitting structures C1 and C2 during a laser-lift off process. Inorder to electrically connect the first and second light-emittingstructures C1 and C2 to each other, a conductive substrate may be used.The substrate 1306 may be formed of a conductive material containing anyone of Au, Ni, Al, Cu, W, Si, Se, and GaAs, for example, Si—Al alloys.Here, according to the selected material, the substrate 1306 may beformed by plating or bonding.

The conductive vias v, provided in the second electrical connectionportion 1307, are internally connected to the second conductivity typesemiconductor layer 1301. In order to reduce contact resistance, thenumber, shape, and pitch of the conductive vias v, and a contact areabetween the conductive vias v and the second conductivity typesemiconductor layer 1301 may be appropriately controlled. Here, sincethe conductive vias v need to be electrically insulated from the activelayer 1302, the first conductivity type semiconductor layer 1303, andthe first conductive contact layer 1304, the insulator 1305 isinterposed therebetween. The insulator 1305 may be formed of anysubstance having electrical insulation. However, since it is desirableto absorb the least amount of light, a silicon oxide or a siliconnitride, such as SiO₂, SiO_(x)N_(y), or Si_(x)N_(y), may be used to formthe insulator 1305.

Like this embodiment, the second conductivity type semiconductor layer1301 is formed through the second electrical connection portion 1307 ata lower portion thereof, there is no need to separately form anelectrode on the upper surface of the second conductivity typesemiconductor layer 1301. Therefore, the amount of light, emitted upwardfrom the second conductivity type semiconductor layer 1301, may beincreased. A light-emitting area will be reduced since the conductivevias v are formed in a portion of the active layer 1302. However, inspite of that, light extraction efficiency will be significantlyimproved since there is no need to form an electrode on the uppersurface of the second conductivity type semiconductor layer 1301.Meanwhile, it can be seen that the entire electrode arrangement of thesecond conductivity type semiconductor layer 1301, according to thisembodiment, is similar to a horizontal electrode structure, rather thana vertical electrode structure, since an electrode is not disposed onthe upper surface of the second conductivity type semiconductor layer1301. However, sufficient current spreading effects can be ensured dueto the conductive vias v formed inside the second conductivity typesemiconductor layer 1301. Furthermore, an uneven structure may be formedon the upper surface of the second conductivity type semiconductor layer1301 to thereby increase the possibility that light incident in adirection of the active layer 1302 is emitted to the outside.

As described above, the semiconductor light emitting device 1300 may bedriven by AC power. To this end, as shown in FIG. 79, the first andsecond light-emitting structures C1 and C2 form an n-p junction. Thisn-p junction may be formed in such a manner that the second electricalconnection portion v of the first light-emitting structure C1 and thefirst electrical connection portion 1304 of the second light-emittingstructure C2 are connected to each other, external power is applied tothe first electrical connection portion 1304 of the light-emittingstructure C1 and the second electrical connection portion 1307 of thesecond light-emitting structure C2. Specifically, in FIG. 79A, terminalsA and B correspond to the first electrical connection portion 1304 ofthe first light-emitting structure C1 and the second electricalconnection portion 1307 of the second light-emitting structure C2,respectively. A terminal C corresponds to the substrate 1306. Here, asshown in FIG. 79B, when the terminals A and B are connected to eachother, and an AC signal is applied to the terminals A and B connected toeach other and the terminal C, an AC light emitting device may berealized.

FIGS. 80 through 82 are cross-sectional views schematically illustratingmodified embodiments of the semiconductor light emitting device of FIG.78. An electrical connection structure between light-emitting structuresof the semiconductor light emitting device according to the modifiedembodiment, as shown in FIGS. 80 through 82, is different from that ofthe above-described embodiment. A circuit diagram of the realizedsemiconductor light emitting device is the same as that of FIG. 80.First, in a semiconductor light emitting device 1400, first and secondlight-emitting structures C1 and C2 are disposed on a substrate 1406.Here, the first light-emitting structure C1 has the same configurationas the first light-emitting structure of FIG. 78. Unlike theabove-described embodiment, a vertical electrode structure can be usedas a part of the light-emitting structure. Specifically, the secondlight-emitting structure C2 corresponds to a vertical electrodestructure. Specifically, a first conductivity type semiconductor layer1403, an active layer 1402, and a second conductivity type semiconductorlayer 1401 may be sequentially formed on the first electrical connectionportion 1404 connected to the substrate 1406. A second electricalconnection portion 1407 is formed on the second conductivity typesemiconductor 1401.

Then, the embodiments of FIGS. 81 and 82 have configurations in whichthe substrates are formed of electrically insulating materials as shownin FIGS. 78 and 79, respectively. In a semiconductor light emittingdevice 1500, as shown in FIG. 81, first and second light-emittingstructures C1 and C2 are disposed on a substrate 1506 having electricalinsulation. Here, like the embodiment of FIG. 78, the first and secondlight-emitting structures C1 and C2 each have a first conductivity typesemiconductor layer 1503, an active layer 1502, and a secondconductivity type semiconductor layer 1501 stacked upon each other in asequential manner on a substrate 1506. Second electrical connectionportions 1507 a and 1507 b have conductive vias v connected to thesecond conductivity type semiconductor layer 1501. Furthermore, aninsulator 1505 is formed in order that the second electrical connectionportions 1507 a and 1507 b are electrically insulated from the firstelectrical connection portion 1504, the first conductivity typesemiconductor layer 1503, and the active layer 1502. As the substrate1506 having electrical insulation is used, the second electricalconnection portion 1507 a of the first light-emitting structure C1 isconnected to the first electrical connection portion 1504 of the secondlight-emitting structure C2 by portions extended in parallel with thesubstrate 1506 from the conductive vias v.

In a similar manner, like the embodiment of FIG. 80, in a semiconductorlight emitting device 1600, as shown in FIG. 82, a second light-emittingstructure C2 has a first conductivity type semiconductor layer 1603, anactive layer 1602, and a second conductivity type semiconductor layer1601 formed on a first electrical connection portion 1604 in asequential manner. A second electrical connection portion 1607 is formedon the second conductivity type semiconductor 1601. As the substrate1606 having electrical insulation is used, a second electricalconnection portion 1607 a of a first light-emitting structure C1 isextended in parallel with the substrate 1606 to the secondlight-emitting structure C2 from conductive vias v connected to thesecond conductivity type semiconductor layer 1601. Therefore, the firstand second light-emitting structures C1 and C2 may share the secondelectrical connection portion 1607 a.

Meanwhile, as for the above-described embodiments, an AC driven lightemitting device is realized using two light-emitting structures.However, the light-emitting structure, that is, the number of lightemitting diodes and a connection structure thereof may vary. FIG. 83 isa circuit diagram illustrating the semiconductor light emitting deviceaccording to this embodiment. In FIG. 83, one diode is a light emittingdiode and corresponds to a light-emitting structure. The circuitdiagram, shown in FIG. 83, is a so-called ladder network circuit and hasfourteen light-emitting structures. In this embodiment, when a forwardvoltage is applied, nine light-emitting structures are operated. Evenwhen a reverse voltage is applied, nine light-emitting structures areoperated. To this end, there are provided three basic electricalconnection structures. As shown in FIG. 83, these three electricalconnection structures are an n-p junction, an n-n junction, and a p-pjunction. Examples of the n-p junction, the n-n junction, and the p-pjunction will be described below. By using these basic junctions, an ACdriven light emitting device having many different numbers of lightemitting diodes and circuit configurations can be obtained.

First, FIGS. 84 and 85 are cross-sectional views schematicallyillustrating an example of an n-p junction. Referring to FIGS. 84 and85, the first and second light-emitting structures C1 and C2 forming ann-p junction are disposed on substrates 1706 and 1706′. The first andsecond light-emitting structures C1 and C2 have a first conductivitytype semiconductor layer 1703, an active layer 1702, and a secondconductivity type semiconductor layer 1701 sequentially stacked on afirst electrical connection portion 1704. An insulator 1705 is formed inorder to electrically insulate conductive vias v, internally connectedto the second conductivity type semiconductor layer 1701, from the firstelectrical connection portion 1704, the first conductivity typesemiconductor layer 1703, and the active layer 1702. A second electricalconnection portion 1707 of the first light-emitting structure C1 isconnected to the first electrical connection portion 1704 of the secondlight-emitting structure C2. Here, the configuration of FIG. 84, usingthe conductive substrate 1706, and the configuration of FIG. 85, usingthe electrical insulating substrate 1706′, create slightly differentshapes of the second electrical connection portion 1707, which aresimilar to the configurations of FIGS. 78 and 81, respectively. However,since in order to implement AC driving, the n-p junction is connected toanother light-emitting structure to form the entire device, rather thanbeing solely used, the second electrical connection portion provided inthe second light-emitting structure C2, that is, the conductive vias vmay be electrically connected to another light-emitting structure ratherthan a structure for applying an external electrical signal.

Then, FIGS. 86 through 88 are cross-sectional views schematicallyillustrating an example of an n-n junction. Referring to FIGS. 86through 88, first and second light-emitting structures C1 and C2 formingan n-n junction are disposed on substrates 1806 and 1806′. The first andsecond light-emitting structures C1 and C2 each have a configuration inwhich a first conductivity type semiconductor layer 1803, an activelayer 1802, and a second conductivity type semiconductor layer 1801 aresequentially stacked on a first electrical connection portion 1804.Here, an insulator 1805 is formed in order to electrically insulateconductive vias v, internally connected to the second conductivity typesemiconductor layer 1801, from the first electrical connection portion1804, the first conductivity type semiconductor layer 1803, and theactive layer 1802. In order to form an n-n junction, the secondelectrical connection portions 1807 of the first and secondlight-emitting structures C1 and C2 need to be connected to each other.For example, as shown in FIG. 86, conductive vias v, provided in firstand second light-emitting structures C1 and C2, may be connected to eachother through a conductive substrate 1806. Furthermore, as shown in FIG.87, when an electrically insulating substrate 1806′ is used, the secondelectrical connection portion 1807 can connect conductive vias v,individually provided in first and second light-emitting structures C1and C2, through a portion extended in parallel with the substrate 1806′.In addition to a connecting method using an electrical connectionportion, a second conductivity type semiconductor layer 1801′ may beused according to a method similar to that described in FIG. 88. Firstand second light-emitting structures C1 and C2 may share the secondconductivity type semiconductor layer 1801′. In this case, an n-njunction may be formed without separately connecting conductive vias v.

Finally, FIGS. 89 through 91 are cross-sectional views schematicallyillustrating an example of a p-p junction. With reference to FIGS. 89through 91, first and second light-emitting structures C1 and C2 forminga p-p junction are disposed on substrates 1906 and 1906′. The first andsecond light-emitting structures C1 and C2 each have a firstconductivity type semiconductor layer 1903, an active layer 1902, and asecond conductivity type semiconductor layer 1901 stacked upon eachother in a sequential manner on a first electrical connection portion1904. Here, an insulator 1905 is formed in order that conductive vias v,individually internally connected to the second conductivity typesemiconductor layer 1901, are electrically insulated from the firstelectrical connection portion 1904, the first conductivity typesemiconductor layer 1903, and the active layer 1902. In order to form ap-p junction, the first electrical connection portions 1904 of the firstand second light-emitting structures C1 and C2 need to be connected toeach other. Here, the conductive vias v may be connected to anotherlight-emitting structure (not shown), which forms the entire AC lightemitting device. As an example of a p-p junction, as shown in FIG. 89,the first electrical connection portions 1904, individually provided inthe first and second light-emitting structures C1 and C2, may beconnected to each other through the substrate 1906 (not shown). Here, asshown in FIG. 90, when the substrate 1906′, having electricalinsulation, is used, a connecting metallic layer 1908 is separatelydisposed to thereby connect the first electrical connection portions1904 individually provided in the first and second light-emittingstructures C1 and C2. Alternatively, without employing a separateconnecting metallic layer, as shown in FIG. 91, a configuration in whichthe first and second light-emitting structures C1 and C2 share the firstelectrical connection portion 1904 may also be employed.

A semiconductor light emitting device according to another exemplaryembodiment of the invention will now be described with reference toFIGS. 92 through 102.

FIG. 92 is a cross-sectional view illustrating a vertical semiconductorlight emitting device according to this embodiment. FIGS. 93 and 94 areviews illustrating a modified embodiment of the vertical semiconductorlight emitting device of FIG. 92.

Referring to FIG. 92, a vertical semiconductor light emitting device2000 according to this embodiment includes n-type and p-typesemiconductor layers 2001 and 2003 and an active layer 2002 interposedtherebetween, thereby forming a light-emitting structure. A reflectivemetal layer 2004 and a conductive substrate 2005 are formed under thelight-emitting structure. An n-type electrode 2006 is formed on then-type semiconductor layer 2001, and a passivation layer 2007 having anuneven structure is formed to cover the side surfaces of thelight-emitting structure.

The n-type semiconductor layer 2001 and the p-type semiconductor layer2003 may be typically formed of nitride semiconductors. That is, then-type semiconductor layer 2001 and the p-type semiconductor layer 2003may be formed of semiconductor materials doped with an n-type impurityand a p-type impurity satisfying an equation ofAl_(x)In_(y)Ga_((1-x-y))N (where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1 aresatisfied), for example, GaN, AlGaN, and InGaN. The n-type impurity mayinclude Si, Ge, Se, Te or the like. The p-type impurity may include Mg,Zn, Be, or the like. Meanwhile, an uneven structure may be formed on theupper surface of the n-type semiconductor layer 2001 in order toincrease the efficiency of light being emitted in a vertical direction.

The active layer 2002, formed between the n-type and p-type nitridesemiconductor layers 2001 and 2003, emits a predetermined amount ofenergy by electron-hole recombination and may have a multiple quantumwell (MQW) structure in which quantum well layers and quantum barrierlayers alternate with each other. As for the multiple quantum wellstructure, an InGaN/GaN structure may be widely used.

The first conductive contact layer 2004 may reflect light, emitted fromthe active layer 2002, upward from the semiconductor light emittingdevice 2000, and may be formed of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn,Pt, or Au. Here, though not illustrated in detail, the first conductivecontact layer 2004 may have a dual or multi-layered structure to therebyincrease reflection efficiency. For example, the first conductivecontact layer 2004 may have a structure of Ni/Ag, Zn/Ag, Ni/Al, Zn/Al,Pd/Ag, Pd/Al, Ir/Ag, Ir/Au, Pt/Ag, Pt/Al, or Ni/Ag/Pt. However, in thisembodiment, the reflective metal layer 2004 is not necessarily included.The reflective metal layer 2004 may also be removed.

The conductive substrate 2005 serves as a p-type electrode and a supportholding the light-emitting structure, that is, the n-type semiconductorlayer 201, the active layer 2002, and the p-type semiconductor layer2003 during a laser-lift off process to be described below. Here, theconductive substrate 2005 may be formed of a material containing Si, Cu,Ni, Au, W, or Ti. Here, according to the selected material, theconductive substrate 2005 may be formed using plating or bonding.

The passivation layer 2007 is an insulating layer formed to protect thelight-emitting structure, and particularly, the active layer 2002.Further, the passivation layer 2007 is formed on a partially removedregion of the light-emitting structure. Specifically, in addition to theside surfaces of the light-emitting structure, as shown in FIG. 92, thepassivation layer 2007 may be formed on a portion of the upper surfaceof the n-type semiconductor layer 2001 and the upper surface of thereflective metal layer 2004. Here, when the reflective metal layer 2004is not used, the passivation layer 2007 is formed on the upper surfaceof the conductive substrate 2005. When the side surfaces exposed bypartially removing the light-emitting structure may be inclined upwardas shown in FIG. 92, this structure may increase a light-emitting areaand may further facilitate the formation of the passivation layer 2007.

The passivation layer 2007 may be formed of a silicon oxide or a siliconnitride, such as SiO₂, SiO_(x)N_(y), or Si_(x)N_(y), in order to performa protection function, and may have a thickness of approximately 0.1 to2 μm. Therefore, the passivation layer 2007 may have a refractive indexof approximately 1.4 to 2.0. It may be difficult for light from theactive layer 2002 to be emitted to the outside due to the difference inrefractive index between the passivation layer 2007 and air or a moldingstructure of a package. In particular, in the vertical semiconductorlight emitting device 2000 according to this embodiment, the p-typesemiconductor layer 2003 has a relatively small thickness. For thisreason, light, emitted toward the side of the active layer 2002, can beemitted to the outside only when this light passes through thepassivation layer 2007. Since light, emitted in a lateral directiontoward the passivation layer 2007 from the active layer 2002, has a verysmall incidence angle with respect to the passivation layer 2007, itbecomes more difficult for the light to be emitted to the outside.

In this embodiment, an uneven structure is formed on the passivationlayer 2007 to thereby increase external light extraction effects. Inparticular, as shown in FIG. 92, when the uneven structure is formed ata region through which the light, emitted in the lateral direction ofthe active layer 2002, passes, the amount of light emitted towards theside of the vertical semiconductor light emitting device 2000 may beincreased. Here, the region, through which light, emitted along thelateral direction of the active layer 2002, passes, may be considered aregion of the upper surface of the reflective metal layer 2004, at whichthe light-emitting structure is not formed. According to simulationresults, a configuration according to this embodiment has increasedlight extraction efficiency by approximately 5% or higher than anotherconfiguration having the same components except for the passivationlayer 2007 employing the uneven structure. Meanwhile, though notnecessarily required in this embodiment, the uneven structure of thepassivation layer 2007 may also be formed on the upper surface of then-type semiconductor layer 2001 to thereby increase vertical lightextraction efficiency.

As shown in FIGS. 93 and 94, a region where an uneven structure of apassivation layer is formed may vary in order to maximize external lightextraction effects. As shown in FIG. 93, an uneven structure may beformed to the side surfaces of a passivation layer 2007′. Furthermore,as shown in FIG. 94, an uneven structure may also be formed on a lowersurface of the passivation layer 2007′, that is, a surface facing thereflective metal layer 2004. Here, a pattern having a shapecorresponding thereto may be formed on the reflective metal layer 2004.

FIGS. 95 through 98 are cross-sectional views for describing a method ofmanufacturing a vertical semiconductor light emitting device having astructure described with reference to FIG. 92.

As shown in FIG. 95, an n-type semiconductor layer 2001, an active layer2002 and a p-type semiconductor layer 2003 are grown sequentially on asubstrate 2008 for semiconductor single-crystal growth by using aprocess such as MOCVD, MBE, or HVPE. The substrate 2008 forsemiconductor single-crystal growth may utilize sapphire, SiC, MgAl₂O₄,MgO, LiAlO₂, LiGaO₂, GaN or the like. In this case, the sapphire, acrystal having Hexa-Rhombo R3c symmetry, has lattice constants of 13.001Å along the c-axis orientation and 4.758 Å along the a-axis orientation,respectively, and has a C(0001) plane, an A(1120) plane, and an R(1102)plane. In this case, since the C plane is stable at high temperaturesand ensures the relatively easy growth of a nitride thin film, it iscommonly used as a substrate for nitride growth.

Subsequently, as shown in FIG. 96, a reflective metal layer 2004 and aconductive substrate 2005 are formed on the p-type semiconductor layer2003 using a method such as plating or sub-mount bonding. Thereafter,although not shown in detail, the substrate 2008 for semiconductorsingle crystal growth is removed using an appropriate lift-off processsuch as laser lift-off or chemical lift-off.

Thereafter, as shown in FIG. 97, a resultant light emitting structure ispartially removed for the purpose of dicing it in the unit of devicesand forming a passivation layer. In this case, a side surface exposed bythe removal may be sloped upward. Furthermore, a process such as wetetching is performed on the top surface of the n-type semiconductorlayer 2001, which is exposed by the removal of the substrate forsemiconductor signal crystal growth, thereby forming an uneven structurethat is contributive to enhancing light extraction efficiency in avertical direction.

Thereafter, as shown in FIG. 98, a passivation layer 2007 for protectingthe light emitting structure is formed. This process may be carried outby appropriately depositing, for example, a silicon oxide or a siliconnitride. An uneven structure may be formed in the light emitting surfaceof the passivation layer 2007 to thereby enhance luminous efficiency ina lateral direction. In this case, this uneven structure may be formedby appropriately using a dry-etching or wet-etching process known in theart. Also, if necessary, the uneven structure may formed even in anotherlight emitting surface of the passivation layer 2007. After theformation of the passivation layer 2007, an n-type electrode is formedon the top surface of the n-type semiconductor layer 2001, therebycompleting a structure illustrated in FIG. 92.

The present invention provides a semiconductor light emitting devicehaving a modified structure from the above vertical structure in orderto further enhance electrical characteristics and opticalcharacteristics.

FIG. 99 is a schematic cross-sectional view illustrating a semiconductorlight emitting device according to another exemplary embodiment of thepresent invention. Referring to FIG. 99, a semiconductor light emittingdevice 2100, according to this embodiment, includes a conductivesubstrate 2105, a light emitting structure including a firstconductivity type semiconductor layer 2103, an active layer 2102 and asecond conductivity type semiconductor layer 2101 sequentially formed onthe conductive substrate 2105, a second conductivity type electrode 2106applying an electrical signal to the second conductivity typesemiconductor layer 2101, and a passivation layer 2107 having an unevenstructure and disposed on the side surface of the light emittingstructure. In FIG. 99, the active layer 2102 is placed on a relativelyupper level as compared to the structure shown in FIG. 92 or the like.However, the active layer 2102 may be placed at various locations, andmay, for example, be located at a similar height to that of the lowerportion of the passivation layer 2107.

In the previous embodiment, that is, in the vertical semiconductor lightemitting device, the n-type electrode is formed on the surface of then-type semiconductor layer exposed when removing the sapphire substrate.However, according to this embodiment, an n-type electrode is exposed tothe outside from under the n-type semiconductor layer by using aconductive via. In detail, the second conductivity type electrode 2106includes conductive vias v penetrating the first conductivity typesemiconductor layer 2104 and the active layer 2102 and connected to thesecond conductivity type semiconductor layer 2101 within the secondconductivity type semiconductor layer 2101, and an electrical connectionportion P extending therefrom and exposed to the outside of the lightemitting structure. In this case, the second conductivity type electrode2106 needs to be electrically separated from the conductive substrate2105, the first conductivity type semiconductor layer 2103, and theactive layer 2102. Therefore, an insulator 2108 is formed appropriatelyaround the second conductivity type electrode 2106. Any material havinga low level of electrical conductivity is usable as the insulator 2108;however, a material with a low level of light absorbency is preferred.For example, the insulator 2108 may be formed of the same material asthe passivation layer 2107.

The second conductivity type electrode 2106 may be formed of a metallicmaterial that can form an ohmic-contact with the second conductivitytype semiconductor layer 2101. Also, the second conductivity typeelectrode 2106 may be formed entirely of the same material.Alternatively, the electrical connection portion P may be formed of adifferent material from another part of the second conductivity typeelectrode 2106, in consideration of the fact that the electricalconnection portion P may be used as a bonding pad portion. Regarding thepreviously described manufacturing process, the first and secondconductivity type semiconductor layers 2101 and 2103 may be p-type andn-type semiconductor layers in general, but the present invention is notlimited thereto. As shown in FIG. 99, a first contact layer 2104 may beformed as an additional element between the first conductivity typesemiconductor layer 2103 and the conductive substrate 2105, and mayutilize a metal having a high level of reflectivity, such as Ag or Al.In this case, the first contact layer 2104 and the second conductivitytype electrode 2106 are electrically separated from each other by theinsulator 2108.

The above electrical connection structure allows the second conductivitytype semiconductor layer 2101 to receive an electrical signal from itsinside rather than from above. Notably, no electrode is formed on thesecond conductivity type semiconductor layer 2101, thereby achieving anincrease in light emitting area. In addition, the conductive vias V,formed in the second conductivity type semiconductor layer 2101, maycontribute to enhancing a current spreading effect. In this case,desired electrical characteristics can be attained by appropriatelycontrolling, for example, the number, area and shape of the conductivevias V. According to this embodiment, the main process such as theformation of the conductive substrate, the removal of the sapphiresubstrate or the like adopts the process of manufacturing a verticalsemiconductor light emitting device, but the device shape obtained bysuch process is rather similar to a horizontal structure. In thisregard, the structure according to this embodiment may be referred to asa combination structure of vertical and horizontal structures.

As in the previous embodiment, the passivation layer 2107 is formed onthe side surface or the like of the light emitting structure, and has anuneven structure on the path of light emitted from the active layer2102, thereby enhancing the extraction efficiency of light emitted in alateral direction from the active layer 2102 toward the passivationlayer 2107. Furthermore, as shown in FIG. 99, an uneven structure mayalso be formed on the top surface of the second conductivity typesemiconductor layer 2101. Although not shown, an uneven portion may alsobe formed on the sloped side surface of the passivation layer 2107.

FIG. 100 is a schematic cross-sectional view illustrating asemiconductor light emitting device having a modified structure of thatdepicted in FIG. 99. An exemplary embodiment depicted in FIG. 100further includes an etch stop layer 2109 in the structure depicted inFIG. 99. Thus, only the etch stop layer 2109 will now be described. Theetch stop layer 2109 is formed on a portion of at least the conductivesubstrate 2105 on which the light emitting structure is absent, and isformed of a material (e.g., an oxide such as SiO₂) that shows adifferent etching characteristic for a specific etching method from asemiconductor material (e.g., a nitride semiconductor) used in the lightemitting structure. An etching depth can be controlled by the etch stoplayer 2109 since the light emitting structure can be etched only up to aregion where the etch stop layer 2109 is located. In this case, the etchstop layer 2109 and the insulator 2108 may be formed of the samematerial for ease of the process. When the light emitting structure isetched in order to, for example, expose the second conductivity typeelectrode 2106 to the outside, this may result in current leakage due tothe deposition of the material of the conductive substrate 2105 or thefirst contact layer 2104 on the side surface of the light emittingstructure. Therefore, the etch stop layer 2109 is formed in advanceunder the light emitting structure, which is to be removed by etching,thereby minimizing the above-mentioned problem.

FIG. 101 is a schematic cross-sectional view illustrating asemiconductor light emitting device according to another exemplaryembodiment of the present invention. FIG. 102 illustrates a structurefurther including an etch stop layer in the structure depicted in FIG.101. Referring to FIG. 101, a semiconductor light emitting device 2200,according to this embodiment, includes a conductivity substrate 2205, alight emitting structure that includes a first conductivity typesemiconductor layer 2203, an active layer 2202 and a second conductivitytype semiconductor layer 2201 sequentially formed on the conductivesubstrate 2205, a first contact layer 2204 applying an electrical signalto the first conductivity type semiconductor layer 2203, conductive viasv extending from the conductive substrate 2205 up to the inside of thesecond conductivity type semiconductor layer 2201, and a passivationlayer 2207 formed on the side surface of the light emitting structureand having an uneven structure.

As for differences from the structure described with reference to FIG.99, the conductive substrate 2205 is electrically connected with thesecond conductivity type semiconductor layer 2201, and the first contactlayer 2204 connected with the first conductivity type semiconductorlayer 2203 includes an electrical connection portion P and is thusexposed to the outside. The conductive substrate 2205 may beelectrically separated from the first contact layer 2204, the firstconductivity type semiconductor layer 2203, and the active layer 2202 byan insulator 2208. That is, this embodiment of FIG. 101 has a structuraldifference from the embodiment of FIG. 99 in that, in FIG. 101, thefirst contact layer 2204, connected with the first conductivity typesemiconductor layer 2203, is exposed to the outside to thereby providethe electrical connection portion P, whereas, in FIG. 99, the secondconductivity type electrode 2106, connected with the second conductivitytype semiconductor layer 2101, is exposed to the outside to therebyprovide the electrical connection portion P. Effects obtained from thisstructure other than this difference regarding electrical connectionsare identical to those described with reference to FIG. 99. As shown inFIG. 102, an etch stop layer 2209 may also be provided. However, thestructure in which the first contact layer 2204 is exposed to theoutside according to this embodiment depicted in FIG. 101 may actuallyfacilitate the process of forming the insulator 2208, as compared to theembodiment depicted in FIG. 99.

<Light Emitting Device Package and Light Source Module>

A light emitting device package, according to the present invention,includes the above semiconductor light emitting device.

Hereinafter, a light emitting device package including a semiconductorlight emitting device will be described according to various exemplaryembodiments of the present invention.

FIG. 103 is a schematic view illustrating a white light emitting devicepackage according to an exemplary embodiment of the present invention.

As shown in FIG. 103, a white light emitting device package 3010,according to this embodiment, includes a blue light emitting device3015, and a resin encapsulant 3019 encapsulating the blue light emittingdevice 3015 and having an upwardly convex lens shape.

The resin encapsulant 3019, employed in this embodiment, is illustratedas having a hemispheric lens shape for ensuring a wide orientation. Theblue light emitting device 3015 may be mounted directly onto a separatecircuit board. The resin encapsulant 3019 may be formed of a siliconresin, an epoxy resin or a combination thereof. Green phosphors 3012 andred phosphors 3014 are dispersed within the resin encapsulant 3019.

The green phosphor 3012, applicable to this embodiment, may be at leastone selected from the group consisting of a silicate-based phosphor ofM₂SiO₄:Eu,Re, a sulfide-based phosphor of MA₂D₄:Eu,Re, a phosphor ofβ-SiAlON:Eu,Re, and an oxide-based phosphor of M′A′₂O₄:Ce,Re′.

Here, M denotes at least two elements selected from the group consistingof Ba, Sr, Ca and Mg, A denotes at least one selected from the groupconsisting of Ga, Al and In, D denotes at least one selected from thegroup consisting of S, Se and Te, M′ denotes at least one selected fromthe group consisting of Ba, Sr, Ca and Mg, A′ denotes at least oneselected from the group consisting of Sc, Y, Gd, La, Lu, Al and In, Redenotes at least one selected from the group consisting of Y, La, Ce,Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, F, Cl, Br and I, and Re′denotes at least one selected from the group consisting of Nd, Pm, Sm,Tb, Dy, Ho, Er, Tm, Yb, F, Cl, Br and I. Furthermore, Re and Re′ areadded at 1 ppm to 50000 ppm in amount.

The red phosphors 3014, applicable to this embodiment, are at least oneselected from the group consisting of nitride-based phosphors ofM′AlSiN_(x):Eu,Re (1≦x≦5) and sulfide-based phosphors of M′D:Eu,Re.

Here, M′ denotes at least one selected from the group consisting of Ba,Sr, Ca and Mg, D denotes at least one selected from the group consistingof S, Se and Te, A′ denotes at least one selected form the groupconsisting of Sc, Y, Gd, La, Lu, Al and In, Re denotes at least oneselected from the group consisting of Y, La, Ce, Nd, Pm, Sm, Gd, Tb, Dy,Ho, Er, Tm, Yb, Lu, F, Cl, Br and I. Re is added at 1 ppm to 50000 ppm.

According to the present invention, specific green phosphors andspecific red phosphors are combined in due consideration of a halfamplitude, a peak wavelength and/or conversion efficiency, so that whitelight having a high color rendering index of 70 or higher can beprovided. Since light in various wavelength bands is obtained bymultiple phosphors, color reproducibility can be enhanced.

The dominant wavelength of the blue light emitting device may range from430 nm to 455 nm. In this case, in order to increase a color renderingindex by ensuring a wide spectrum in a visible light band, the peakwavelength of light, emitted from the green phosphors 3012, may rangefrom 500 nm to 550 nm, and the peak wavelength of light, emitted fromthe red phosphors 3014, may range from 610 nm to 660 nm.

The blue light emitting device may have an half amplitude ranging from10 nm to 30 nm, and the green phosphors may have a half amplituderanging from 30 nm to 100 nm, and the red phosphors may have a halfamplitude ranging from 50 nm to 150 nm.

According to another exemplary embodiment of the present invention,yellow or yellowish orange phosphors may be used in addition to the redphosphors 3014 and the green phosphors 3012. This may ensure an improvedcolor rendering index. An associated embodiment is illustrated in FIG.104.

Referring to FIG. 104, a white light emitting device package 3020,according to this embodiment, includes a package body 3021 having areflective cup in its center, a blue light emitting device 3025 mountedon the bottom of the reflective cup, and a transparent resin encapsulant3029 encapsulating the blue light emitting device 3025 in the reflectivecup.

The resin encapsulant 3029 may be formed of, for example, a siliconresin, an epoxy resin or a combination thereof; however, the inventionis not limited thereto. According to this embodiment, the resinencapsulant 3029 contains yellow phosphors or yellowish orange phosphors3026 in addition to green phosphors 3022 and red phosphors 3012 that arethe same as those described with reference to FIG. 103.

That is, the green phosphors 3022 may be at least one selected from thegroup consisting of silicate-based phosphors of M₂SiO₄:Eu,Re,sulfide-based phosphors of MA₂D₄:Eu,Re, phosphors of β-SiAlON:Eu,Re, andoxide-based phosphors of M′A′₂O₄:Ce,Re′. The red phosphors 3024 may beat least one of nitride-based phosphors of M′AlSiN_(x):Eu,Re (1≦x≦5) andsulfide-based phosphors of M′D:Eu,Re.

According to this embodiment, third phosphors 3026 are further included.The third phosphors may be yellow or yellowish orange phosphors that canemit light within an intermediate wavelength band between green and redlight wavelength bands. The yellow phosphors may be silicate-basedphosphors, and the yellowish orange phosphors may be phosphors ofα-SiAlON:Eu,Re.

According to the exemplary embodiments above, two or more kinds ofphosphor powders are mixed and dispersed in a single resin encapsulantregion; however they may be variously modified in structure. In greaterdetail, the two or three kinds of phosphors may be provided inrespectively different layers. For example, the green phosphors, the redphosphors and the yellow or yellowish orange phosphors may be providedas a multilayer phosphor structure by distributing powders thereof underhigh pressure.

Alternatively, the phosphor structure may be implemented as multilayerphosphor-containing resin layers.

Referring to FIG. 105, a white light emitting device package 3030,according to this embodiment, includes a package body 3031 having areflective cup in its center, a blue light emitting device 3035 mountedon the bottom of the reflective cup, and a transparent resin encapsulant3039 encapsulating the blue light emitting device 3035 in the reflectivecup, as in the previous embodiment.

Resin layers, each containing different kinds of phosphors, are providedon the resin encapsulant 3039. That is, a wavelength conversion part maybe configured such that it has a first resin layer 3032 containing thegreen phosphors, a second resin layer 3034 containing the red phosphors,and a third resin layer 30306 containing the yellow or yellowish orangephosphors.

The phosphors used in this embodiment may be identical or similarphosphors to those described with reference to FIG. 104.

White light, obtained by the combination of the phosphors proposed bythe present invention, can ensure a high rendering index. This will nowbe described in more detail with reference to FIG. 106.

Referring to FIG. 106, in a related-art example, yellow phosphors arecombined with a blue light emitting device, thereby obtaining convertedyellow light as well as light in a blue wavelength band. Since theoverall visible light spectrum contains virtually no light from thegreen and red wavelength bands, it is difficult to ensure a colorrendering index close to natural light. Notably, the converted yellowlight has a small half-amplitude in order to achieve high conversionefficiency, which further lowers the color rendering index.

Comparative to the above, in an inventive example, green phosphors G andred phosphors R are combined with a blue light emitting device. Sincelight is emitted in green and red wavelength bands, unlike in the caseof the comparative example, a wider spectrum can be obtained in thevisible light band, thereby significantly enhancing a color renderingindex. Additionally, the color rendering index can be further enhancedby adding yellow or yellowish orange phosphors that can emit light in anintermediate wavelength band between the green and red wavelength bands.

With reference to FIGS. 107A through 109B, the green phosphors, the redphosphors, and the selectively added yellow and yellowish orangephosphors, employed in the present invention, will now be described.

FIGS. 107A through 109B illustrate the wavelength spectrums of phosphorsproposed by the present invention, regarding light generated from a bluelight emitting device (about 440 nm).

FIGS. 107A through 107D illustrate spectrums regarding green phosphorsemployed in the present invention.

First, FIG. 107A illustrates the spectrum of silicate-based phosphors ofM₂SiO₄:Eu,Re where M denotes at least two selected from the groupconsisting of Ba, Sr, Ca and Mg, Re denotes at least one selected fromthe group consisting of Y, La, Ce, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm,Yb, Lu, F, Cl, Br and I, and Re is in the range of 1 ppm to 50,000 ppm.Converted green light has a peak wavelength of about 530 nm, and a halfamplitude of about 65 nm.

FIG. 107B illustrates the spectrum of oxide-based phosphors ofM′A′₂O₄:Ce,Re′, where M′ denotes at least one selected from the groupconsisting of Ba, Sr, Ca and Mg, A′ denotes at least one selected fromthe group consisting of Sc, Y, Gd, La, Lu, Al and In, Re′ is at leastone selected from the group consisting of Nd, Pm, Sm, Tb, Dy, Ho, Er,Tm, Yb, F, Cl, Br and I, and Re′ is in the range of 1 ppm to 50,000 ppm.Converted green light has a peak wavelength of about 515 nm, and a halfamplitude of about 100 nm.

FIG. 107C illustrates the spectrum of sulfide-based phosphors ofMA₂D₄:Eu,Re where M denotes at least two selected from the groupconsisting of Ba, Sr, Ca and Mg, A denotes at least one selected fromthe group consisting of Ga, Al and In, D denotes at least one selectedfrom the group consisting of S, Se and Te, Re denotes at least oneselected from the group consisting of La, Ce, Nd, Pm, Sm, Gd, Tb, Dy,Ho, Er, Tm, Yb, Lu, F, Cl, Br and I, and Re is in the range of 1 ppm to50,000 ppm. Converted green light has a peak wavelength of about 636 nmand a half amplitude of about 60 nm.

FIG. 107D illustrates the spectrum of phosphors of β-SiAlON:Eu,Re whereRe denotes at least one selected from the group consisting of Y, La, Ce,Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, F, Cl, Br and I, and Re isin the range of 1 ppm to 50,000 ppm. Converted green light has a peakwavelength of about 540 nm, and a half amplitude of about 45 nm.

FIGS. 108A and 108B illustrate the spectrums of red phosphors employedin the present invention.

FIG. 108 a illustrates the spectrum of nitride-based phosphors ofM′AlSiN_(x):Eu,Re (1≦x≦5) where M′ denotes at least one selected fromthe group consisting of Ba, Sr, Ca and Mg, Re denotes at least oneselected from the group consisting of Y, La, Ce, Nd, Pm, Sm, Gd, Tb, Dy,Ho, Er, Tm, Yb, Lu, F, Cl, Br and I, and Re is in the range of 1 ppm to50,000 ppm. Converted red light has a peak wavelength of about 640 nm,and a half amplitude of about 85 nm.

FIG. 108B illustrates the spectrum of sulfide-based phosphors ofM′D:Eu,Re where M′ denotes at least one selected from the groupconsisting of Ba, Sr, Ca and Mg, D denotes at least one selected fromthe group consisting of S, Se and Te, Re denotes at least one selectedfrom the group consisting of Y, La, Ce, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er,Tm, Yb, Lu, F, Cl, Br and I, and Re is in the range of 1 ppm to 50000ppm. Converted red light has a peak wavelength of about 655 nm and ahalf amplitude of about 55 nm.

FIGS. 109A and 109B illustrate the spectrums of yellow or yellowishorange phosphors selectively employed in the present invention.

FIG. 109A illustrates the spectrum of silicate-based phosphors.Converted yellow light has a peak wavelength of about 555 nm and a halfamplitude of about 90 nm.

FIG. 109B illustrates the spectrum of phosphors of α-SiAlON:Eu,Re whereRe denotes at least one selected from the group consisting of Y, La, Ce,Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, F, Cl, Br and I, and Re isin the range of 1 ppm to 50,000 ppm. Converted yellow light has a peakwavelength of about 580 nm and a half amplitude of about 35 nm.

According to the present invention, specific green phosphors andspecific red phosphors are combined or yellow or yellowish orangephosphors are added to this combined phosphors in consideration of thehalf amplitude, the peak wavelength and/or conversion efficiency.Accordingly, white light having a high color rendering index of 70 orhigher can be provided.

When the dominant wavelength of the blue light emitting device rangesfrom 430 nm to 455 nm, the peak wavelength of light emitted from thegreen phosphors may range from 500 nm to 550 nm, and the peak wavelengthof light emitted from the red phosphors may range from 610 nm to 660 nm.The peak wavelength of light emitted from the yellow or yellowish orangephosphors may range from 550 nm to 600 nm.

When the blue light emitting device has a half amplitude ranging from 10nm to 30 nm, the green phosphors may have a half amplitude ranging from30 nm to 100 nm, and the red phosphors may have a half amplitude rangingfrom 50 nm to 150 nm. The yellow or yellowish orange phosphors may havea half amplitude ranging from 20 nm to 100 nm.

According to the present invention, a wide spectrum can be ensured in avisible light band according to the selections and combinations of thephosphors, and superior white light having a higher color renderingindex can be provided.

Such a light emitting device package may provide a white light sourcemodule that can be useful as a light source for an LCD backlight unit.Namely, the white light source module, according to this embodiment, mayconstitute a backlight assembly as a light source for an LCD backlightunit by being combined with various optical members such as a diffusingplate, a light guide plate, a reflective plate and a prism sheet. FIGS.110 and 111 illustrate such white light source module.

Referring to FIG. 110, a light source module 3100 for an LCD backlightincludes a circuit board 3101 and an array of a plurality of white lightemitting device packages mounted on the circuit board 3101. A conductivepattern (not shown), connected with LED devices 3010, may be formed onthe top surface of the circuit board 3101.

Each of the white light emitting device packages 3010 may be understoodas a white light emitting device package described with reference toFIG. 103. That is, the blue light emitting device 3015 is mounteddirectly on the circuit board 3101 by using a chip-on-board (COB)method. Each of the white light emitting device packages 3010 includesthe hemispherical resin encapsulant 3019 equipped with a lens functionand having no separate reflective wall, thereby attaining a wide angleof orientation. The wide angle of orientation of each white light sourcemay contribute to reducing the size (thickness or width) of an LCD.

Referring to FIG. 111, a light source module 3200 for an LCD backlightincludes a circuit board 3201 and an array of a plurality of white lightemitting device packages 3020 mounted on the circuit board 3201. Asdescribed above with reference to FIG. 104, the white light emittingdevice package 3020 includes the blue light emitting device 3025 mountedin the reflective cup of the package body 3021, and the resinencapsulant 3029 encapsulating the blue light emitting device 3025. Theresin encapsulant 3029 may contain the yellow or yellowish orangephosphors 3026 dispersed therein, as well as the green and red phosphors3022 and 3024.

FIG. 112 is a cross-sectional view illustrating a light emitting devicepackage according to another exemplary embodiment of the presentinvention.

Referring to FIG. 112, a light emitting device package 400, according tothis embodiment, includes a light emitting device 4011, electrodestructures 4012 and 4013, a package body 4015, a transmissivetransparent resin 4016 and a recess 4018 on which the light emittingdevice 4011 is mounted.

The light emitting device 4011 is bonded and connected with one set ofthe ends of the (metallic) wires 4014 a and 4014 b. The electrodestructures 4012 and 4013 are bonded and connected with the other set ofthe ends of the pair of wires 4014 a and 4014 b, respectively.

Here, the light emitting devices according to the above-describedexemplary embodiment of the present invention may be used as the lightemitting device 4011 of this embodiment.

The package body 4015 is a molded structure obtained byinjecting-molding a resin material, and includes a cavity 4016 having aclosed bottom and an open top.

Here, the cavity 4017 has an upper slope surface inclined at apredetermined angle. A reflective member 4017 a, formed of a metallicmaterial having a high reflectivity such as Al, Ag or Ni, may beprovided on the upper slope surface so as to reflect light generatedfrom the reflective member 4017 a.

The package body 4015 is fixed by the pair of electrode structures 4012and 4013 molded integrally with the package body 4015. The top surfaceof each of the electrode structures 4012 and 4013 has one end portionexposed to the outside through the bottom of the cavity 4017.

The other end portion of each of the electrode structures 4012 and 4013is exposed to the outside of the package body 4015 and is connected withan external power source.

The recess 4018 is formed by downwardly recessing the top surfaces ofthe electrode structures 4012 and 4013, exposed in the bottom of thecavity 4017, to a predetermined depth. Here, the recess 4018 may beformed in one electrode structure 4012 of the pair of electrodestructures 4012 and 4013 on which the light emitting device 4011 ismounted.

The recess 4018 is provided in the form of a downwardly bent portion atone end portion of the electrode structure 4012 where at least one lightemitting device 4011 is mounted. This bent portion includes a flatmounting surface on which the light emitting device 4011 is mounted, anda pair of lower slope surfaces respectively extending upward at apredetermined angle from the left and right sides of the mountingsurface and facing the outer surface of the light emitting device 4011.

The lower slope surfaces 4012 a and 4013 a may be provided with areflective member to reflect light generated from the light emittingdevice 4011.

The recess 4018 may formed at a depth H ranging from 50 μm to 400 μm indue consideration of the height h of the mounted light emitting device4011. This may reduce the height H of the cavity 4017 of the packagebody up to 150 μm to 500 μm, and also reduce the amount of transmissivetransparent resin filled in the cavity 4017. Accordingly, manufacturingcosts can be reduced, light intensity can be enhanced, and a reductionin the overall size of products can be achieved.

FIG. 113 is a cross-sectional view illustrating a light emitting devicepackage according to a modified embodiment from the embodimentillustrated in FIG. 112.

As shown in FIG. 113, the light emitting device package, according tothis modified embodiment, includes a hole 4018 a instead of the recess4018, between the opposing end portions of the pair of electrodestructures 4012 and 4013. The hole 4018 a is formed by recessing thebottom of the cavity 4017 to a predetermined depth when the package body4015 is molded.

In this modified embodiment, elements other than the hole 4018 a areidentical to those of the light emitting device package according to theexemplary embodiment of FIG. 112, and the descriptions thereof will beomitted.

The transmissive transparent resin 4016 is formed of a transparent resinmaterial such as epoxy, silicon or resin. Such a transparent resinmaterial is filled in the cavity 4017 in order to cover and protect thelight emitting device 4011 and wires 4014 a and 4014 b against externalconditions.

Here, the transmissive transparent resin 4016 may include one ofwavelength converting phosphors among YAG-, TAG-, silicate-, sulfide- ornitride-based phosphors capable of converting light, generated from thelight emitting device 4011, into white light.

The YAG- and TAG-based phosphors may be selected from (Y, Tb, Lu, Sc,La, Gd, Sm)3(Al, Ga, In, Si, Fe)5(O, S)12:Ce, and the silicate-basedphosphors may be selected from (Sr, Ba, Ca, Mg)2SiO4: (Eu, F, Cl). Thesulfide-based phosphors may be selected from (Ca,Sr)S:Eu,(Sr,Ca,Ba)(Al,Ga)2S4:Eu. The nitride-based phosphors may be selectedfrom phosphor components of (Sr, Ca, Si, Al, O)N:Eu (e.g., CaAlSiN4:Euβ-SiAlON:Eu) or Ca-α SiAlON:Eu-based (Cax,My)(Si,Al)12(O,N)16 where Mdenotes at least one of Eu, Tb, Yb and Er, 0.05<(x+y)<0.3, 0.02<x<0.27and 0.03<y<0.3.

The white light may be generated by combining a blue (B) light emittingdevice with yellow (Y) phosphors, green (G) and red (R) phosphors, oryellow (Y), green (G) and red (R) phosphors. The yellow, green and redphosphors are excited by the blue light emitting device to therebyrespectively emit yellow light, green light and red light. The yellowlight, the green light and the red light are mixed with a part of bluelight emitted from the blue light emitting device, so that the whitelight is output.

A detailed description of those phosphors for white-light output hasbeen made in detail in the above-described embodiments, and thus isomitted in this modified example.

Lower slope surfaces 4012 b and 4013 b may be formed at the end portionsof the electrode structures 4012 and 4013 facing the outer surface ofthe light emitting device 4011 mounted in the hole 4018 a. In this case,a reflective member is provided on the lower slope surfaces 4012 b and4013 b and reflects light emitted from the light emitting device 4011.

As for the light emitting device packages 4000 and 4000′, the lightemitting device 4011 disposed at the very center of the cavity 4017 ismounted on the mounting surface of the recess formed by downwardlybending the electrode structure 4012, or in the hole 4018 a formedbetween the opposing end portions of the electrode structures 4012 and4013. Accordingly, the top surface of the light emitting device 4011,wire-bonded with the electrode structures 4012 and 4013 using the wires4014 a and 4014 b, may be located on roughly the same level as the topsurfaces of the electrode structures 4012 and 4013.

Accordingly, the maximum height of the wires 4014 a and 4014 bwire-bonded with the light emitting device 4011 can be lowered by thelowered mounting height of the light emitting device 4011.

This reduction in height ensures a reduction in the amount oftransmissive transparent resin 4016 filled in the cavity to protect thelight emitting device 4011 and the wires 4014 a and 4014 b. Also, thefilling height H of the transmissive transparent resin 4016 can bedecreased by the reduced height of the mounted light emitting device4011. Accordingly, the intensity of light, emitted from the lightemitting device 4011, can be enhanced relative to the related art.

Since the filling height H of the transmissive transparent resin 4016 inthe cavity 4017 is lowered, the level of the top of the package body4015 is lowered by the lowered filling height. Thus, a reduction in theoverall size of the package can be achieved.

FIGS. 114A through 114C are schematic views illustrating the process ofan external lead frame in the light emitting device package according tothis embodiment.

As shown in FIG. 114A, the electrode structures 4012 and 4013, which arerespectively cathode and anode electrodes, are fixed integrally to thepackage body 4015 injection-molded mostly using a resin material.However, their end portions are exposed to the outer side of the packagebody 4015 and connected with an external power source.

The electrode structures 4012 and 4013, downwardly exposed to theoutside of the package body 4015, are bent toward the side surfaceand/or the bottom surface of the package body such that the electrodestructures 4012 and 4013 are bent in an opposite direction to the lightemitting surface where the cavity 4017 is formed.

The electrode structures 4012 and 4013 are bent toward the side surfaceand/or the back surface (rear or lower portion) of the mounting surface(bottom surface 4019) of the package.

As for the process of forming such electrode structures 4012 and 4013,as shown in FIG. 114B, the end portion of the exposed electrodestructure 4012 is bent first to conform with the shape of the sidesurface of the package 4000, and is then bent rearward of the bottom4019 of the package to thereby complete the overall shape of theelectrode structure 4012 as shown in FIG. 114B.

Hereinafter, a method of manufacturing β-sialon phosphors among theabove-described phosphors, which can be regulated to have high lightintensity and desired particle characteristics.

The method of manufacturing β-sialon phosphors according to the presentinvention relates to manufacturing β-sialon phosphors having a chemicalformula expressed as Si_((6-x))Al_(x)O_(y)N_((6-y)): Lnz where Ln is arare-earth element and 0<x≦4.2, 0<y≦4.2 and 0<z≦1.0 are satisfied. Themethod of manufacturing the β-sialon phosphors includes: preparing araw-material mixture by mixing a base raw material with an activator rawmaterial activating the base raw material, the base raw materialincluding a silicon raw material containing metal silicon, and analuminum raw material including at least one of metal aluminum and analuminum compound; and heating the raw-material mixture in a nitrogenatmosphere

According to the present invention, raw materials are mixed and heatedin a nitrogen atmosphere to thereby manufacture β-sialon phosphors. Theraw materials include silicon, aluminum and a rare-earth metal acting asan activator.

The silicon raw material refers to a raw material containing silicon,and may include only metal silicon or both metal silicon and a siliconcompound mixed therewith. The silicon compound may utilize siliconnitride or silicon oxide.

The metal silicon may be high-purity metal silicon that is in a powderphase with a low content of impurities such as Fe. In the case of metalsilicon powder, the particle size or distribution thereof do not have adirect influence on the particle composition of phosphors. However,depending on the firing conditions or the raw material being mixed, theparticle size or distribution of the silicon powder affects particlecharacteristics such as the particle size and the shape of phosphors,and also affects the light emitting characteristic of the phosphors. Inthis regard, the particle size of the metal silicon powder may be 300 μmor less.

Regarding reactivity, the smaller the particle size of the metal siliconis, the higher the reactivity becomes. However, since the reactivity isalso affected by a raw material being mixed or a firing rate, the metalsilicon does not necessarily have a small particle size, and is notlimited to the powder phase.

The aluminum raw material may include metal aluminum, an aluminumcompound containing aluminum or both. The aluminum compound containingaluminum may be, for example, aluminum nitride, aluminum oxide oraluminum hydroxide. In the event that the metal silicon is used as thesilicon raw material, the aluminum raw material does not need to utilizemetal aluminum and may utilize only the aluminum compound.

In the event that the metal aluminum is used, high-purity metal aluminumthat is in a powder phase with a low content of impurities such as Femay be used. Regarding the above-described viewpoint, the metal aluminummay have a particle size of 300 μm or less. However, since raw materialsbeing mixed or a firing rate have their influence even in the case ofthe metal aluminum, the metal aluminum does not necessarily have a smallparticle size, and is not limited to the powder phase.

The activator raw material may utilize a rare-earth metal selected fromthe group consisting of Eu, Ce, Sm, Yb, Dy, Pr, and Tb. In detail, anexample thereof may include an oxide such as Eu₂O₃, Sm₂O₃, Yb₂O₃, CeO,Pr₇O₁₁ or Tb₃O₄, Eu(NO₃)₃, or EuCl₃. Preferably, the activator rawmaterial may be Eu or Ce.

By controlling a mixing ratio between the silicon raw material and thealuminum raw material, the particle characteristic of the β-sialonphosphors may be controlled. Furthermore, the particle characteristic ofthe β-sialon phosphors may be controlled by controlling a mixing ratiobetween the silicon compound and the metal silicon of the silicon rawmaterial, or a mixing ratio between the aluminum compound and the metalaluminum of the aluminum raw material. The effects of the raw materialsof the metal silicon or the metal aluminum will be described in greaterdetail through inventive examples that will be described later.

The β-sialon phosphors, manufactured according to the present invention,may have the following chemical formula 1: Si(6−x)AlxOyN(6−y): Lnz . . .Chemical formula 1 where Ln is a rare-earth element, and 0<x≦4.2,0<y≦4.2, and 0<z≦1.0 are satisfied. The β-sialon phosphors may be greenlight emitting phosphors, and the peak wavelength thereof may range from500 nm to 570 nm.

As described above, the activator raw material, containing a rare-earthelement such as Eu, Sm, Yb, Ce, Pr of Tb as an activator, is measuredand mixed to the silicon raw material containing the metal silicon, andthe aluminum raw material containing at least one of the metal aluminumand the aluminum compound. Thereafter, a boron nitride (BN) crucible isfilled with this raw-material mixture and is fired at high temperatureunder a nitrogen atmosphere, thereby manufacturing β-sialon phosphors.

Phosphors are produced from the raw-material mixture by being fired at ahigh temperature in the nitrogen atmosphere. Here, the N₂ concentrationin the nitrogen atmosphere may be 90% or higher. Also, the gas pressurein the nitrogen atmosphere may range from 0.1 Mpa tp 20 Mpa. To createthe nitrogen atmosphere, a vacuum state may be formed and a nitrogenatmosphere may be then introduced. Alternatively, the nitrogenatmosphere may be introduced without forming a vacuum state, and it maybe introduced discontinuously.

When the raw-material mixture including the metal silicon is fired inthe nitrogen atmosphere, nitrogen reacts with silicon and thus nitridesthe silicon to thereby form sialon, so that the nitrogen gas serves as anitrogen supply source. At this time, since the silicon, aluminum andthe activator raw material react together before or during the nitridingprocess, sialon with a uniform composition can be manufactured. In sucha manner, the light intensity of the produced β-sialon phosphors can beimproved.

Heating in this firing process may be conducted at a high temperatureranging from 1850° C. to 2150° C. This heating temperature may be variedaccording to the composition of the raw material. However, to producephosphors having high light intensity, the firing may be carried out ata high temperature ranging from 1900° C. to 2100° C. under a gaspressure of 0.8 Mpa or higher. After the heating process, milling orclassification may be performed in order to control the particlecharacteristics of the heated raw-material mixture. The milled orclassified raw-material compound may be re-fired at a high temperature.

Hereinafter, the present invention will now be described in greaterdetail with reference to inventive examples of producing β-sialonphosphors using the method of manufacturing β-sialon phosphors accordingto the present invention.

In the following exemplary embodiments, raw materials are made into amixture by measuring predetermined amounts of activator raw material aswell as silicon and aluminum raw materials, which are the base rawmaterials, and mixing them using a ball mill or a mixer. The resultantraw-material mixture is put into a high-temperature-resistant containersuch as a BN crucible and is then put into an electric furnace wherepressure-firing or vacuum-firing takes place. This is increased intemperature at a temperature-raising rate of 20° C./minute under a gaspressure of 0.2 Mpa to 2 Mpa in a nitrogen atmosphere, and thus heatedto 1800° C. or higher, thereby manufacturing β-sialon phosphors.

Inventive examples 1 through 9 involve manufacturing phosphors byvarying silicon raw materials, the aluminum raw material and the mixingratios therebetween, and comparative examples 1 through 3 involvemanufacturing phosphors using a silicon raw material without metalsilicon.

All the phosphors manufactured according to the inventive examples 1through 9 and the comparative examples 1 through 3 are Eu-activatedβ-sialon phosphors, and are green light emitting phosphors having a peakwavelength ranging from 520 nm to 560 nm.

INVENTIVE EXAMPLE 1

Silicon nitride (Si₃N₄) and metal silicon (Si) were used as a siliconraw material, alumina (Al₂O₃) was used as an aluminum raw material, andeuropium oxide (Eu₂O₃) was used as an activator. Si₃N₄ of 4.047 g, Si of5.671 g, Al₂O₃ of 0.589 g, and Eu₂O₃ of 0.141 g were measured and mixedusing a mixer and a sieve, and was then filled in a BN crucible and setinto a pressure-resistant furnace. In a firing process, heating iscarried out up to 500° C. in a vacuum, and an N₂ gas was introduced at500° C. Under the N₂ atmosphere, the temperature was raised from 500° C.to 1950° C. at 5° C./minute, and firing was performed thereon at 1950°C. under the gas pressure of 0.8 Mpa or higher for five hours.

Cooling was performed after the firing process, and the crucible wastaken out of the electric furnace. Thereafter, phosphors, generatedthrough the firing at the high temperature, were milled and sieved usinga 100-mesh sieve. The phosphors, obtained in the above manner, werewashed and dispersed using hydrofluoric acid and hydrochloric acid, weredried sufficiently, and were classified using a 50-mesh sieve, therebyobtaining phosphors of the inventive example 1.

INVENTIVE EXAMPLE 2

β-sialon phosphors were manufactured using the same method as in theinventive example 1, except that Si₃N₄ of 1.349 g and Si of 7.291 g wereused.

INVENTIVE EXAMPLE 3

β-sialon phosphors were manufactured using the same method as in theinventive example 1, except that Si₃N₄ of 6.744 g and Si of 4.051 g wereused.

INVENTIVE EXAMPLE 4

β-sialon phosphors were manufactured using the same method as in theinventive example 1, except that Si₃N₄ of 9.442 g and Si of 2.430 g wereused.

INVENTIVE EXAMPLE 5

β-sialon phosphors were manufactured using the same method as in theinventive example 1, except that only Si of 8.101 g, rather than Si₃N₄,was used as the silicon raw material.

COMPARATIVE EXAMPLE 1

β-sialon phosphors were manufactured using the same method as in theinventive example 1, except that only Si₃N₄ of 13.488 g, rather than Si,was used as the silicon raw material.

INVENTIVE EXAMPLE 6

Silicon nitride (Si₃N₄) and metal silicon (Si) were used as a siliconraw material, aluminum nitride (AlN) was used as an aluminum rawmaterial, and europium oxide (Eu₂O₃) was used as an activator. Si₃N₄ of5.395 g, Si of 3.241 g, AlN of 0.379 g and Eu₂O₃ of 0.137 g weremeasured and mixed using a mixer and a sieve, and were then filled in aBN crucible and set into a pressure-resistant furnace. In a firingprocess, heating was carried out at 1450° C. for five hours or longerunder a nitrogen atmosphere, and cooling was then conducted. Thereafter,the resultant fired material was milled. The milled fired material wasfilled in the BN crucible again and is set into the pressure-resistantelectric furnace. Subsequently, heating was conducted up to 500° C. in avacuum, and an N₂ gas was introduced at 500° C. Under an N₂ atmosphere,the temperature was raised from 500° C. to 2000° C. at 5° C./minute, andfiring was carried out at 2000° C. under the gas pressure of 0.8 Mpa orhigher for five hours.

Cooling was performed after the firing, and the crucible was taken outof the electric furnace. Thereafter, phosphors, generated through thefiring at a high temperature, were milled and sieved using a 100-meshsieve. The phosphors, obtained in the above manner, were washed anddispersed using hydrofluoric acid and hydrochloric acid, were driedsufficiently, and were classified using a 50-mesh sieve, therebyobtaining phosphors of the inventive example 6.

INVENTIVE EXAMPLE 7

β-sialon phosphors were manufactured using the same method as in theinventive example 6, except that Si₃N₄ of 7.554 g and Si of 1.944 g wereused.

INVENTIVE EXAMPLE 8

β-sialon phosphors were manufactured using the same method as in theinventive example 6, except that only Si of 6.481 g, rather than Si₃N₄,was used as the silicon raw material.

COMPARATIVE EXAMPLE 2

β-sialon phosphors were manufactured using the same method as in theinventive example 6, except that only Si₃N₄ of 10.791 g, rather than Si,was used as the silicon raw material.

INVENTIVE EXAMPLE 9

β-sialon phosphors were manufactured using the same method as in theinventive example 6, except that Si₃N₄ of 6.744 g, Si of 4.051 g, Eu₂O₃of 0.172 g, and only metal aluminum (Al) of 0.312 g rather than Al₂O₃ orAlN as the aluminum raw material were used.

COMPARATIVE EXAMPLE 3

β-sialon phosphors were manufactured using the same method as in theinventive example 9, except that only Si₃N₄ of 13.488 g rather than Sias the silicon raw material, and Al of 0.473 g were used.

The mixing ratios of the raw materials used in the above inventiveexamples and comparative examples are shown in the following Table 2.

TABLE 2 Example Si3N4 number (g) Si (g) Al₂O₃ (g) AlN (g) Al (g) Eu₂O₃(g) Inventive 4.047 5.671 0.589 — — 0.141 example 1 Inventive 1.3497.291 0.589 — — 0.141 example 2 Inventive 6.744 4.051 0.589 — — 0.141example 3 Inventive 9.442 2.430 0.589 — — 0.141 example 4 Inventive —8.101 0.589 — — 0.141 example 5 Comparative 13.488 — 0.589 — — 0.141example 1 Inventive 5.395 3.241 — 0.379 — 0.137 example 6 Inventive7.554 1.944 — 0.379 — 0.137 example 7 Inventive — 6.481 — 0.379 — 0.137example 8 Comparative 10.791 — — 0.379 — 0.137 example 2 Inventive 6.7444.051 — — 0.312 0.172 example 9 Comparative 13.488 — — — 0.473 0.172example 3

The phosphors, manufactured according to the inventive example 1, wereclassified by a powder X-ray diffraction (XRD), and the result thereofis shown in FIG. 115. FIG. 115 and JCPD data confirm that themanufactured phosphors are β-sialon phosphors.

Furthermore, the light emission characteristic thereof was measured byemitting excitation light of 460 nm thereto. FIG. 116 illustrates thelight emission spectrums of the β-sialon phosphors obtained using theinventive example 1 and the β-sialon phosphors obtained using thecomparative example 1. The β-sialon phosphors obtained using theinventive example 1 are green light emitting phosphors having a peakwavelength of 541 nm and a half amplitude of 54.7 nm. The lightintensity thereof is higher than that of the β-sialon phosphors obtainedusing the comparative example 1 by 27%.

The excitation spectrum of the β-sialon phosphors obtained by theinventive example 1 was measured using emission light of 541 nm asdetection light. The result thereof is shown in FIG. 117. It can be seenthat an excitation band exists in an ultraviolet light region and even avisible light region of about 500 nm.

β-sialon phosphors of 7 wt %, obtained by each of the inventive examples1 to 9 and comparative examples 1 to 3, red CaAlSiN3:Eu phosphors of 3wt %, and silicon resin of 10 wt % were appropriately mixed and madeinto a slurry. This slurry is injected into a cup on a mount leadequipped with a blue LED, and is then cured at 130° C. for an hour.Using the resultant phosphors, a white LED was manufactured. The lightintensity of the manufactured white LED was measured.

The peak wavelengths of light, emitted from the β-sialon phosphors,obtained using the inventive examples 1 to 9 and the comparativeexamples 1 to 3, and the light intensity of white LEDs using the sameare shown in Table 3 below (wt %).

TABLE 3 Aluminum Peak wave- silicon raw material raw length(nm) Inten-Example Si/Si₃N₄ material of emitted sity number Kinds (wt %) Kindslight (sb) Inventive Si/Si₃N₄ 70/30 Al₂O₃ 541 127 example 1 InventiveSi/Si₃N₄ 90/10 Al₂O₃ 541 124 example 2 Inventive Si/Si₃N₄ 50/50 Al₂O₃541 124 example 3 Inventive Si/Si₃N₄ 30/70 Al₂O₃ 541 107 example 4Inventive Si — Al₂O₃ 541 118 example 5 Comparative Si₃N₄ — Al₂O₃ 541 100example 1 Inventive Si/Si₃N₄ 50/50 AlN 540 113 example 6 InventiveSi/Si₃N₄ 30/70 AlN 538 115 example 7 Inventive Si — AlN 540 106 example8 Comparative Si₃N₄ — AlN 540 100 example 2 Inventive Si/Si₃N₄ 50/50 Al540 119 example 9 Comparative Si₃N4 — AlN 536 100 example 3

The phosphors, obtained using the inventive examples 1 to 9 and thecomparative examples 1 to 3, emit light having a peak wavelength ofabout 540 nm, and are thus determined to be green light emittingphosphors. The white LEDs using the phosphors, obtained using theinventive examples 1 to 3, have relatively high light intensity levelsranging from 124 to 127.

However, the inventive example 4 in which the content of metal siliconis smaller than the content of silicon nitride, realizes a lower lightintensity level than the light intensity levels in the inventiveexamples 1 to 3 in which the content of the metal silicon is greaterthan the content of silicon nitride. The inventive examples 5 and 8,utilizing only Si as the silicon raw material, realize a lower lightintensity level than the light intensity levels in the inventiveexamples 1, 2, 3 and 6, while realizing a higher light intensity levelthan the light intensity levels of the inventive examples 4, 6 and 7, inwhich the content of metal silicon is smaller than the content ofsilicon nitride. Thus, it can be confirmed that β-sialon phosphorsrealizing high light intensity can be manufactured when using the metalsilicon.

The comparative examples 1 through 3 using only Si₃N₄ as the silicon rawmaterial each realize a light intensity level of 100. Thus, it can beseen that they have lower light intensity levels than when metal siliconis not used as a base raw material as in the inventive examples.

In addition, a high level of light intensity is attained even when bothmetal silicon and metal aluminum are used as in the inventive example 9.

The above-described β-sialon phosphors may be advantageously applied tolight emitting devices and modules that generate white light by thecombination with other phosphors.

<Backlight Unit>

A backlight unit, according to the present invention, includes theabove-described light emitting device package. The light emitting devicepackage, equipped with the semiconductor light emitting device accordingto the present invention, may be used as light sources for variousdevices such as lighting equipment, car headlights and the like, as wellas surface light sources such as backlight units.

Hereinafter, a backlight unit including the light emitting devicepackage will be described according to various embodiments of thepresent invention.

FIGS. 118A and 118B are schematic views illustrating a surface lightsource device including a flat light guide plate, i.e., a backlightunit, according to an exemplary embodiment of the present invention.

As shown in FIG. 118A, a backlight unit 5000 including a flat lightguide plate according to the present invention, is a tandem surfacelight source device, and includes N LED light source modules 5010, and Nflat light guide plates 5020.

Each of the N LED light source modules 5010 includes a board 5011, and aplurality of light emitting device packages 5012 arranged in a row onthe board 5011. The N LED light source modules 5010, configured in theabove manner, are arranged parallel to one another. Each flat lightguide plate 5020 is arranged and installed along one side of acorresponding LED light source module of the N LED light source modules5010.

The backlight unit having the flat light guide plates 5020 may include areflective member (not shown) disposed under the LED light source module5010 and the flat light guide plate 5020 and reflecting light emittedfrom the LED light source module 5010.

Also, an optical sheet (not shown) may be provided on the flat lightguide plate 5020. An example of the optical sheet may include adiffusion sheet diffusing light, output toward a liquid crystal panelafter being reflected by the reflective member and refracted by the flatlight guide plate, in various directions, or a prism sheet collectinglight, having passed through the diffusion sheet, within a front viewingangle.

In more detail, the LED light source module 5010 may include a pluralityof light emitting device packages 5012 each mounted using a top-viewmethod. The flat light guide plate 5020 is a plate-type, and is formedof a transparent material to transmit light and disposed in a directionin which light is emitted from the LED light source. The flat lightguide plate is simple in shape and easy to manufacture as compared to awedge type light guide plate, and facilitates the positioning thereof onan LED light source.

The flat light guide plate 5020 includes a light input portion 5021receiving light emitted from the LED light source module 5010, a lightoutput portion 5024 having a flat plate shape with a uniform thicknessand outputting light, received from the LED light source module, towarda liquid crystal panel as illuminating light, and a leading edge portion5022 protruding from the opposite side to the light input portion 5021with reference to the light output portion 5024, and having a smallerthickness than that of the light input portion 5021. The flat lightguide plate 5020 is disposed such that the leading edge portion 5022thereof covers the LED light source module 5010. Namely, the N+1^(th)LED light source module 5010 is placed under the leading edge portion5022 of the n^(th) flat light guide plate 5020. The bottom of theleading edge portion 5022 of the flat light guide plate 5020 has a prismshape 5023.

As shown in FIG. 118B, light emitted from the light emitting devicepackage 5012 is not directly output to the flat light guide plate 5020but is scattered and dispersed by the prism shape 5023 formed on thebottom of the leading edge portion 5022 of the flat light guide plate5020. Accordingly, hot spots may be removed from the light guide plateover the LED light source module 5010.

FIG. 119 is a schematic perspective view illustrating the flat lightguide plate 5020 depicted in FIGS. 118A and 118B. As shown in FIG. 119,the flat light guide plate 5020 includes the light input portion 5021receiving light emitted from the light source module 5010 including theplurality of light emitting device packages 5012, the light outputportion 5024 having a flat plate shape with a uniform thickness andoutputting light, incident on the light input portion 5021, toward aliquid crystal panel (not shown) as illuminating light, and the leadingedge portion 5022 formed at the opposite side to the light input portion5021 with reference to the light output portion 5024 and having asmaller section than the light incidence section of the light inputportion 5021.

The leading edge portion 5022 has the prism shape 5023 in order todisperse a portion of light emitted from the light emitting devicepackages 5012 arranged thereunder. The prism shape may be at least oneof a triangular prism, a cone prism and a hemispherical prism.

The prism shape of the leading edge portion 5022 may be formed on theentirety of the leading edge portion 5022, or may be formed only overthe light emitting device packages 5012. The prism shape is contributiveto removing hot spots generated on the flat light guide plate 5020 overthe light emitting device packages 5012.

According to the present invention, the prism shape 5023 is formed onthe bottom of the leading edge portion 5022 of the flat light guideplate 5020. Thus, there is no need for performing the process of forminga separate diffusion sheet and a prism sheet between the light emittingdevice package 5012 and the flat light guide plate 5020 in order todisperse hot spots that are generated by a portion of the light, emittedfrom the light emitting device package 5012, over the flat light guideplate 5020.

A backlight unit including a flat light guide plate, according toanother exemplary embodiment of the present invention, will now bedescribed with reference to FIGS. 120 through 125.

FIG. 120 is an exploded perspective view illustrating a backlight unitaccording to another exemplary embodiment of the present invention, FIG.121 is a cross-sectional view taken along line I-I′ of FIG. 120,illustrating the assembled backlight unit. Here, the backlight unit mayinclude a plurality of light guide plates. However, two light guideplates are illustrated for the ease of description.

Referring to FIGS. 120 and 121, a backlight unit 600 includes a lowercover 6010, a light guide plate 6020, a light source device 6030 and afixing member 6040.

The lower cover 6010 has a receiving space. For example, the receivingspace may be formed by a plate constituting the bottom of the lowercover 6010, and the sidewall extending from the edge of the plate in aperpendicular manner.

The lower cover 6010 may include a coupling hole or a coupling portion6011 to which the fixing member 6040 to be described later is coupled.Here, the coupling hole or the coupling portion 6011 may be provided inthe form of a hole portion through which the fixing member 6040penetrates, or a recess portion in which the fixing member 6040 isinserted.

The light guide plate 6020 may provided in the form of a plurality ofdivided light guide plates 6020. The divided light guide plates 6020 aredisposed in the receiving space of the lower cover 6010 in a parallelmanner.

Each of the light guide plates 6020 has through holes 6021 penetratingthe body thereof. The through hole 6021 is disposed at the edge of thelight guide plate 6020. In this embodiment of the present invention, thelocation and number of through holes 6021 is not limited. The throughhole 6021 is located corresponding to the coupling portion 6011.

Although illustrated as having a quadrangular shape, the light guideplate 6020 is not limited to the illustrated shape, but may have variousshapes such as a triangle, a hexagon or the like.

A plurality of light source devices 6030 are disposed at one side ofeach light guide plate 6020 to provide light to the light guide plate6020. Each of the light source devices 6030 may include a light emittingdevice package 6031, a light source that forms light, and a board 6032including a plurality of circuit patterns for supplying the drivingvoltage of the light emitting device package 6031.

For example, the light emitting device package 603 may include sub-lightemitting devices respectively realizing blue, green and red colors. Redlight, green light and red light emitted from the sub-light emittingdevices, realizing blue, green and red colors respectively, are mixed togenerate white light. Alternatively, the light emitting device packagemay include a blue light emitting device and phosphors that convert bluelight from the blue light emitting device into yellow light. At thistime, the blue light and the yellow light are mixed to thereby realizewhite light.

The light emitting device package and the phosphors have already beendescribed above in detail, and thus a description thereof will beomitted.

Light formed by the light source device 6030 is incident on the sidesurface of the light guide plate 6020 and is output upwardly by thetotal internal reflection of the light guide plate 6020.

The fixing member 6040 serves to fix the light guide plate 6020 to thelower cover 6010 so as to prevent the movement of the light guide plate6020. The fixing member 6040 is inserted into the through hole 6021 ofthe light guide plate 5020 to thereby fix the light guide plate 6020onto the lower cover 6010. Furthermore, the fixing member 6040 may becoupled with the coupling portion 6011 by way of the through hole 6021of the light guide plate 120. For example, the fixing member 6040 maypass through the coupling portion 6011 configured as the hole portion orbe inserted into the coupling portion 6011 configured as the recessportion.

The fixing member 6040 includes a body portion 6042, and a head portion6041 extending from the body portion 6042.

The body portion 6042 penetrates the through hole of the light guideplate 6020, and is coupled with the coupling portion 6011. That is, thebody portion 6042 couples the light guide plate 6020 and the lower cover6010 with each other to thereby fix the light guide plate 6020 on thelower cover 6010.

The head portion 6041 has a wider width than the body portion 6042 tothereby prevent the fixing member 6040 from being completely separatedfrom the through hole 6021 of the light guide plate 6020.

The head portion 6041 may have one of various sectional shapes such assemi-circular, semi-oval, quadrangular and triangular shapes. Here, thehead portion 6041, when having a triangular sectional shape, mayminimize contact between the fixing member 6040 and an optical member6060 to be described later, and this may minimize the generation ofblack spots caused by the fixing member 6040.

The light guide plate 6020 and the optical member 6060 are spaced apartfrom each other at a predetermined interval, and thus light emitted fromthe light guide plate 6020 may be uniformly provided on the opticalmember 6060. Here, the head portion 6041 supports the optical member6060 and serves to maintain the interval between the light guide plate6020 and the optical member 6060. Here, the interval between the lightguide plate 6020 and the optical member 6060 may be adjusted bycontrolling the height of the head portion 6041.

The fixing member 6040 may be formed of a light transmissive material,for example transparent plastic, in order to minimize its influence onimage quality.

Furthermore, a reflective member 6050 may be disposed under each of thelight guide plates 6020. The reflective member 6050 reflects lightemitted to the lower side of the light guide plate 6020 and thus causesthe light to be re-incident on the light guide plate 6020, therebyenhancing the light efficiency of the backlight unit.

The reflective member 6050 may include a through portion 6051corresponding to the through hole 6021 and the coupling portion 6011.The fixing member 6040 may be coupled with the coupling portion 6011 byway of the through hole 6021 and the through portion 6051. Accordingly,when the reflective member 6050 is provided in the form of a pluralityof divided reflective members 6050 like the light guide plate 6020, thereflective member 6050 can be fixed on the lower cover 6010 by thefixing member 6040.

Furthermore, the backlight unit may further include the optical member6060 disposed over the light guide plate 6020. An example of the opticalmember 6060 may include a diffusion plate, a diffusion sheet, a prismsheet and a protective sheet disposed over the light guide plate 6020.

Thus, according to this embodiment of the present invention, thebacklight unit includes a plurality of divided light guide plates,thereby further enhancing a local dimming effect through local driving.

Also, the plurality of divided light guide plates are fixed on the lowercover using the fixing member, thereby preventing defects caused by themovement of the light guide plate.

Moreover, since the fixing member can maintain the uniform intervalbetween the light guide plate and the optical member, light can beuniformly provided to a liquid crystal panel.

FIG. 122 is a plan view illustrating an LED backlight unit according toanother exemplary embodiment of the present invention. FIG. 123 is across-sectional perspective view illustrating region A indicated in FIG.122 before a board is coupled, and FIG. 124 is a cross-sectionalperspective view illustrating the region A indicated in FIG. 122 afterthe board is coupled. FIG. 125 is a cross-sectional view taken alongline II-II′ of FIG. 124.

As shown in FIGS. 122 through 125, an LED backlight unit, according tothe present invention, includes a lower cover 6110, a plurality of lightguide plates 6120, a board 6131, a plurality of LED packages 6132, and afixing member 6140. The lower cover 6110 has a coupling hole or portionprovided in the form of a first through hole 6110 a or a recess. Theplurality of light guide plates 6120 are disposed on the lower cover6110. The board 6131 is disposed at one side of each of the light guideplates 6120 in a manner parallel to the bottom of the bottom of thelower cover 6110, includes wires receiving voltage from the outside, andhas a second through hole 6131 a corresponding (or facing) the firstthrough hole 6110 a of the lower cover 6110. The plurality of lightemitting device packages 6132 are mounted on the board 6131 provided atone side of a corresponding light guide plate of the light guide plates6120. The fixing member 6140 is coupled with the second through hole6131 a of the board 6131 and/or the first through hole 6110 a of thelower cover 6110, and press the edge portions of the adjacent lightguide plates 6120.

Here, the lower cover 6110 has the first through hole 6110 a penetratinga plate in the form of, for example, a circular, rectangular or ovalshape (alternatively, a coupling recess recessed in the plate). Here,the plate serves as the bottom of the receiving space of the lower cover6110. Such a lower cover 6110 is formed of material such as iron (Fe) orelectrolytic galvanized iron (EGI). Also, the lower cover 6110 may havea sidewall, namely, a side frame extending upwardly from the edge of theplate, serving as the bottom, in a perpendicular manner. The bottom ofthe lower frame may be divided into a plurality of regions arranged in arow in order to realize a backlight unit capable of local dimming. Theplurality of regions may be bordered by a recess or the like. Of course,the recess, bordering the plurality of regions, corresponds to areceiving recess for the board 6131 as will be described later.

The first through hole 6110 a in the lower cover 6110 may have variousshapes besides a circular, oval or rectangular shape. However, the firstthrough hole 6110 a may have two parallel longer sides and two shortersides formed with a predetermined curvature at both ends of the twolonger sides so as to connect the two longer sides. Here, the firstthrough hole 6110 a may be formed such that the longer axis (Y-axis) ofthe first through hole 6110 a is located in the same direction as thedirection in which light moves. Even when the coupling recess, ratherthan the first through hole 6110 a, is formed, the coupling recess hasthe same structural characteristic as described above.

A reflective plate (not shown) is attached to the entirety of the bottomof the lower cover 6110. Alternatively, when a receiving recess isformed in the bottom of the lower cover 6100, a plurality of reflectiveplates (not shown) are respectively attached on a plurality of bottomregions other than the receiving recess. The reflective plate utilizes awhite polyester film or a film coated with metal such as Ag or Al. Thevisible light reflectance of the reflective plate ranges from about 90%to 97%. The thicker the coated film is, the higher the reflectancebecomes.

The plurality of reflective plates on the bottom of the lower cover 6110may each extend so as to be placed between the light emitting devicepackages 6132 providing light and the light guide plate 6120 adjacent tothe back of the light emitting device package 6132. In this case,induced light provided from one side of the light guide plate 6120 maybe reflected again by the reflective plate without being interrupted bythe light emitting device package 6132 disposed at the opposite side ofthe light guide plate 6120. Then, the reflected light may be providedtoward an optical member (not shown) provided at the upper side, therebyenhancing the light reflection efficiency.

An LED light source 6130 is provided in the receiving recess of thelower cover 6110 or at one side of the light guide plate 6120. The LEDlight source 6130 includes the board 6131, i.e., a printed circuit board(PCB), and the light emitting device package 6132 mounted on the board6131. The board 6131 is provided in, for example, the receiving recessto thus be placed on the same horizontal level as the bottom of thelower cover 6110, includes wires for receiving voltage from the outside,and has a second through hole 6131 a corresponding to the first throughhole 6110 a of the lower cover 6110.

The board 6131 has the second through hole 6131 a formed between thelight emitting device package 6132 and the light emitting device package6132. The board 6131 having the second through hole 6131 a is providedon the bottom of the lower cover 6110 such that the second through hole6131 a corresponds to (or faces) the first through hole 6110 a of thelower cover 6110. The second through hole 6131 a in the board 6131 mayhave, for example, a circular or oval shape like the first through hole6110 a of the lower cover 6110. However, according to the presentinvention, the second through hole 6131 a may have two parallel longersides and two shorter sides formed with a predetermined curvature atboth ends of the two longer sides so as to connect the two longer sides.At this time, the second through hole 6131 a is formed such that thedirection of the longer axis (X-axis) of the second through hole 6131 abecomes perpendicular to the direction in which light moves.Accordingly, the second through hole 6131 a of the board 6131 has itslonger axis (X-axis) crossing the longer axis (Y-axis) of the firstthrough hole 6110 a of the lower cover 6110.

The size of the second through hole 6131 a formed in the board 6131,more precisely, the interval between the two longer sides thereof, maybe associated with the diameter of the body of the fixing member 6140including a screw thread. This is because the size of the second throughhole 6131 a may affect the interval between the light emitting devicepackage 6132 providing light and the light guide plate 6120 receivingand inducing light provided from the light emitting device package 6132.This will be described later.

In addition, the light emitting device package 6132 includes a packagebody 6133 fixed on the board 6131, forming an exterior frame and havinga receiving recess, a light emitting device 6136 mounted in thereceiving recess of the package body 6133 and providing light, and apair of first and second electrode structures (not shown) exposed in thereceiving recess, electrically connected with a wire formed on the board6131, and on which the light emitting device 6135 is mounted.

In the case that the light emitting device 6136 is a blue light emittingdevice, the light emitting device package 6132 may additionally includea resin encapsulant 6136 in the receiving recess in order to providewhite light. Here, the resin encapsulant 6136 may include yellowphosphors. For example, the resin encapsulant 6136 may be formed byinjecting a gel-phase epoxy resin containing YAG-based yellow phosphorsor a gel-phase silicon resin containing YAG-based yellow phosphors intothe receiving recess of the package body 6133, and subsequentlyperforming UV curing or thermal curing thereon.

Of course, the present invention is not limited to the light emittingdevice package 6132 including the blue light emitting device and theyellow phosphors. For example, the light emitting device package 6132may include a near ultraviolet chip and a resin encapsulant provided onthe near ultraviolet chip and containing a mixture of red, green andblue phosphors. Also, the resin encapsulant may be formed bysequentially stacking layers respectively containing red, green and bluephosphors.

The plurality of light guide plates 6120 are provided on the bottom ofthe lower cover 6110 divided into a plurality of regions, respectively.In this case, the side surface of the light guide plate 6120 may beadhered to the package body 6133, so that light, provided from the lightemitting device 6135 mounted in the receiving recess of the package body6133, can be induced into the light guide plate 6120 without loss.

The light guide plate 6120 is formed of PMMA, and as PMMA has the lowestlight absorbency in a visible light region among polymer materials, itthus has significantly high transparency and gloss. The light guideplate 6120, formed of PMMA, is not broken or deformed due to its highmechanical strength, and has high visible-light transmittance of 90% to91% and considerably low internal loss. Also, this light guide plate6120 has superior chemical properties, resistance and mechanicalproperties such as tensile strength and bending strength.

The fixing unit 6140 is coupled to the board 6131 between the lightguide plates 6120. The fixing member 6140 is formed of a transparentmaterial and has a screw-like shape. The fixing member 6140 is coupledby penetrating the second through hole 6131 a of the board 6131 and thefirst through hole 6110 a of the lower cover 6110 corresponding to thesecond through hole 6131. Thus, the fixing member 6140 fixes theadjacent light guide plates 6120 placed at both sides of the lightemitting device package 6132, that is, at the front side outputtinglight and the back side opposite to the front side, while maintaining auniform interval between the light guide plates.

Here, the fixing member 6140, according to the present invention, isformed of a transparent material, so that light, induced in the lightguide plate 6120, can be provided to the optical member above withoutinterruption. The fixing member 6140 may be formed of the same materialas the light guide plate 6120.

The fixing member 6140, according to the present invention, includes ahead portion that may have various shapes such as a circular orquadrangular shape, and a body portion extending from the head portionand having a cylindrical shape or the like. The fixing member 6140 maybe fixed to the second through hole 6131 a of the board 6131 and/or thefirst through hole 6110 a of the lower cover 6110 by using a screwthread formed on the outer surface of the body portion of the fixingmember 6140. Of course, the body portion of the fixing member 6140 mayhave a square column shape.

The head portion has a size large enough to cover the interval betweenthe light guide plates 6120, and the edge of the light guide plates 6120in part. Thus, the size of the head portion may be slightly varieddepending on the interval between the light guide plates 6120, and thediameter of the body portion may be the same as the interval between thetwo parallel longer sides of the second through hole 6131 a of the board6131 and/or the first through hole 6110 a of the lower cover 6110.

Furthermore, the size of the head portion of the fixing unit 6140 or thediameter of the body portion thereof may be slightly varied depending onthe size of the second through hole 6131 a of the board 6131 describedabove. For example, when the size of the second through hole 6131 a ofthe board 6131 is small, the diameter of the body portion of the fixingmember 6140 is also small. This may mean that the interval between thelight emitting device package 6132 and the light guide plate 6120 can bereduced.

When the fixing member 6140 is coupled with the board 6131 and/or thelower cover 6110 in a screw-like manner, the head portion of the fixingmember 6140 presses the upper edge portions of the adjacent light guideplates 6120 disposed on the board 6131 to which the light emittingdevice package 6132 is fixed. Accordingly, the movements of the lightguide plates 6120 can be prevented even under external shock.

Also, a nut may be coupled to a portion of the fixing member 6140exposed to the outside through the first through hole 6110 a of thelower cover 6110, so that the fixing member 6140 can attain reinforcedstrength.

Consequently, the fixing member 6140 coupled on the board 6131 may serveas a spacer between the light emitting device package 6132 and the lightguide plate 6120. Thus, the fixing member 6140 maintains a uniforminterval between the light emitting device package 6132 and the lightguide plate 6120, thereby becoming capable of coping with the shrinkageand/or expansion of the light guide plate 6120.

Of course, the fixing member 6140 is not limited to having a screwthread. For example, as shown in FIG. 121, the fixing member 6140 may beprovided as a screw having a head portion and an opposite hooked endportion. In this case, the fixing member 6140 penetrates the secondthrough hole 6131 a of the board 6131 and the first through hole 6110 aof the lower cover, and is fixed to the lower cover 6110 by the hookedend portion.

An optical member (not shown) is provided above the plurality of lightguide plates in order to supplement the optical characteristic of lightprovided through the light guide plates 6120. Here, the optical membermay include a diffusion plate having a diffusion pattern to reduce thenon-uniformity of light transmitted through the light guide plates 6120,and a prism sheet having a condensing pattern for enhancing the frontintensity of light.

By the above construction according to the present invention, the fixingmember 6410 is provided between the light guide plates 6120 so as to fixthe light guide plates 6120 while maintaining a uniform intervaltherebetween. This construction can prevent the movement of the lightguide plates 6120, caused by external shock, and cope with the shrinkageof the light guide plates 6120 in a direction (X-axis) perpendicular tothe direction in which light moves.

The second through hole 6131 a of the board 6131, having a longer axisand a shorter-axis direction, can deal with the shrinkage of the board6131 in the longer-axis direction (X-axis) of the second through hole6131 a.

Furthermore, the fixing member 6140 is coupled with the first throughhole 6110 a having a longer-axis (Y-axis) in the direction that lightmoves. Thus, even if the light guide plate 6120 shrinks and/or expands,the light guide plate 6120, the fixing member 6140 and/or the board 6131can move together along the longer axis (Y-axis) of the first throughhole 6110 a of the lower cover 6110. Accordingly, the uniform intervalbetween the light guide plate 6120 and the light emitting device package6132 can be maintained, bright spots and bright lines can be furtherprevented as compared to the related art.

A liquid crystal display according to the present invention may includethe LED backlight unit according to the above exemplary embodiments, andmay further include a liquid crystal panel (not shown) provided on theoptical member.

Here, the liquid crystal display may further include a mold structurecalled a main support in order to prevent the warp of the display devicecaused by external shock. The backlight unit is provided under the mainsupport, and the liquid crystal panel is loaded on the main support.

The liquid crystal panel includes a thin film transistor array substrateand a color filter substrate that are attached together, and a liquidcrystal layer injected between these two substrates.

Signal lines such as gate lines and data lines cross one another on thethin film transistor array substrate, and thin film transistors (TFT)are formed at the respective crossings of the data and gate lines. TheTFT transfers video signals, which are to be sent to liquid crystalcells of the liquid crystal layer from the data lines, that is, red (R),green (G) and blue (B) data signals, in response to scan signalsprovided through the gate lines. Also, pixel electrodes are formed inthe pixel regions between the data and gate lines.

The color filter substrate includes thereon, a black matrix formedcorresponding to the gate and data lines of the thin film transistorarray substrate, color filters formed in regions defined by the blackmatrix to provide red (R), green (G) and blue (B) colors, and a commonelectrode provided on the black matrix and the color filters.

Data pads extending from the data lines and gate pads extending from thegate lines are formed at the edge of the thin film transistor arraysubstrate attached with the color filter substrate. A gate driver and adata driver are respectively connected to the data pads and the gatepads, and supply signals thereto.

An upper cover may be provided on the liquid crystal panel. Here, theupper cover covers the four sides of the liquid crystal panel and isfixed to the lower cover 210 or the sidewall of the main support. Ofcourse, the upper cover is formed of the same material as the lowercover 210.

As set forth above, according to exemplary embodiments of the invention,the semiconductor light emitting device includes a first electrodehaving a portion formed on a light-emitting surface and the otherportion disposed under an active layer, thereby maximizing thelight-emitting area.

Since the electrode is uniformly disposed on the light emitting surface,the current can be spread stably even when high operating current isapplied thereto.

Furthermore, the uniform current spreading can be achieved to therebyreduce current crowding during high-current operation and thus enhancereliability.

While the present invention has been shown and described in connectionwith the exemplary embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

The invention claimed is:
 1. A semiconductor light emitting device,comprising: a conductive substrate; a light emitting structure having asecond semiconductor layer, an active layer, and a first semiconductorlayer sequentially disposed on the conductive substrate, the firstsemiconductor layer having first and second surfaces, the first surfacebeing adjacent to the active layer and the second surface being oppositeto the first surface; a second electrode layer including at least oneexposed region formed by exposing a portion of an interface between thesecond electrode layer and the second semiconductor layer, the exposedregion extending toward a side surface of the light emitting structurethat is exposed outwardly of the light emitting structure; a firstelectrode layer penetrating the second electrode layer, the secondsemiconductor layer, and the active layer and being electricallyconnected to the first semiconductor layer by being extended toward thesecond surface of the first semiconductor layer through a plurality ofcontact holes penetrating predetermined regions of the firstsemiconductor layer, the first electrode layer being electricallyconnected to the conductive substrate by being in contact with theconductive substrate; an insulating layer electrically separating thefirst electrode layer from the second electrode layer, the secondsemiconductor layer, and the active layer by being disposed between thefirst electrode layer and the second electrode layer and on sidesurfaces of the contact holes; and an electrode pad portion disposed onthe exposed region of the second electrode layer.
 2. The semiconductorlight emitting device of claim 1, wherein the contact holes areuniformly arranged.
 3. The semiconductor light emitting device of claim1, wherein the number of the contact holes is 1 to 48,000.
 4. Thesemiconductor light emitting device of claim 1, wherein the contact areabetween the first electrode layer and the first semiconductor layer is6,150 μm² to 156,800 μm² per 1,000,000 μm² area of the semiconductorlight emitting device.
 5. The semiconductor light emitting device ofclaim 2, wherein a distance between central points of adjacent contactholes among the contact holes is 5 μm to 500 μm.
 6. The semiconductorlight emitting device of claim 1, wherein the exposed region of thesecond electrode layer is formed at a corner of the semiconductor lightemitting device.
 7. The semiconductor light emitting device of claim 1,wherein the second electrode layer elects light generated from theactive layer.
 8. The semiconductor light emitting device of claim 1,wherein the second electrode layer includes one selected from the groupconsisting of Ag, Al, Pt, Ni, Pt, Pd, Au, Ir and a transparentconductive oxide.
 9. The semiconductor light emitting device of claim 1,wherein the conductive substrate includes one selected from the groupconsisting of Au, Ni, Al, Cu, W, Si, Se, and GaAs.
 10. The semiconductorlight emitting device of claim 1, wherein the contact area between thefirst electrode layer and the first semiconductor layer is 3% to 13% ofa total area of the second surface of the light emitting structure. 11.The semiconductor light emitting device of claim 1, wherein a contactarea between the first electrode layer and the first semiconductor layeris 0.615% to 15.68% of a total area of the second surface of the lightemitting structure.
 12. The semiconductor light emitting device of claim1, wherein the first electrode layer has a substantially flat shapeexcept for a region in which the contact holes are disposed.
 13. Thesemiconductor light emitting device of claim 1, wherein the secondelectrode layer has a substantially flat shape.